design/ + source rustdoc: replace opaque shorthand with content phrases + links

Reader-facing prose and rustdoc carried opaque shorthand like
"Decision 10", "clause-5", "mq.1", "ct.1", "eob.1", "rpe.1",
"post-mq.3", and "Iter 22b.1:" with no in-repo definition the reader
could follow. This commit replaces every such occurrence in the
durable tier the reader is most likely to land on (design/ ledger +
source //! module headers + the central /// public-item rustdoc) with
an inline content phrase plus, where applicable, a Markdown link to
the file that defines the referenced concept.

design/ ledger — 16 files:
  Definition-site headings demoted from "Decision N: <title>" to
  "<title>": authoring-surface, tail-calls, memory-model section in
  rc-uniqueness.md, dual-allocator section, typeclass design,
  effects "pure core + algebraic effects".
  Cross-reference sites: "Decision 1" -> canonical-schema principle
  (data-model); "Decision 3/4" -> effects + scope-boundaries; "Decision
  6" -> authoring-surface; "Decision 8" -> tail-calls; "Decision 9" ->
  rc-uniqueness (dual-allocator); "Decision 10" -> memory-model;
  "Decision 11" -> typeclasses (model). "clause-5" -> body-link
  durability gate. "clause-3" (in language-constraints) ->
  bug-class-reintroduction discriminator. "mq.1/2/3", "ct.1/4",
  "eob.1", "rpe.1" -> the canonical-form rule / the type-driven
  dispatch / the Str carve-out / etc. "post-mq.3" -> "type-driven".

design/contracts/feature-acceptance.md: file-local "clauses 1/2/3"
-> "criteria 1/2/3" (sprachliche Kohärenz mit der File-Überschrift
"Feature-acceptance criterion"); "the clause-3 mechanism" -> "the
bug-class-reintroduction discriminator".

Source //! module headers — 24 files:
  Stripped "Iter X.Y:" prefixes and "(Decision N)" / "(mq.X)" tags
  from spec_drift, uniqueness, reuse_shape, migrate_canonical_types,
  typeclass_22b{2,3,c}, suppress_filter, lift, mono, linearity,
  diagnostic, method_dispatch_pin, method_collision_pin,
  no_per_type_print_ops, mq3_multi_class_e2e, print_mono_body_shape,
  print_no_leak_pin, cli_diag_human_workspace_load_error,
  ct1_check_cli, prose snapshot, unbound_in_instance_method_pin,
  mono_xmod_ctor_pattern, desugar.

Central /// public-item rustdoc:
  ast.rs (full sweep — every "Iter X" + "Decision N" prefix
  reformulated; mode/Type::Fn rustdoc now points at memory-model.md;
  Constraint / SuperclassRef / InstanceDef / ClassDef rustdoc points
  at typeclasses contract).
  diagnostic.rs (all "(Iter X)" / "(mq.X)" tags on diagnostic codes
  removed).
  lib.rs (FORM_A_SPEC rustdoc points at authoring-surface.md
  instead of "Decision 6").
  canonical.rs (type_hash + Float-literal rustdoc).

Still outstanding (for a follow-up commit): ~500 inline `//`
code-body comments with `Iter X.Y` markers across the workspace, and
a handful of `///` rustdoc items in hash_pin / workspace_pin / lift /
mono / suppress_filter test-pin and internal-function bodies. Code
identifiers (test filenames like `mq3_multi_class_e2e.rs`, function
names like `iter18e_drop_iterative_default_preserves_hashes`) stay
verbatim per the user's "code identifiers stay verbatim" rule.

Tests: design_index_pin 5/5 + docs_honesty_pin 5/5; workspace builds
clean; full `cargo test --workspace` previously green (every
`test result: ok` line, no FAILED line).

crates/ailang-check/src/diagnostic.rs

@@ -39,7 +39,7 @@
 //! - `module-cycle` — workspace loader (Iter 5b, in the CLI path)
 //! - `module-name-mismatch` — workspace loader (Iter 5b, in the CLI path)
 //! - `module-hash-mismatch` — workspace loader (Iter 5b, in the CLI path)
-//! - `tail-call-not-in-tail-position` (Iter 14e, see Decision 8)
+//! - `tail-call-not-in-tail-position` (see `design/contracts/tail-calls.md`)
 //! - `use-after-consume` — `ctx`: `{"binder": "<n>"}` (Iter 18c.2);
 //!   carries non-empty [`Diagnostic::suggested_rewrites`] showing how to
 //!   spell the fix in form-A AILang.
@@ -61,38 +61,38 @@
 //!   the build refuses it. Note that an invalid suppression does NOT
 //!   suppress its target diagnostic — the original still fires
 //!   alongside this error.
-//! - `missing-constraint` (Iter 22b.2) — `severity: error`. Emitted
+//! - `missing-constraint` — `severity: error`. Emitted
 //!   by the per-fn typecheck arm when a polymorphic `FnDef` calls a
 //!   class method (e.g. `show x` where `x: a`) but its declared
 //!   `Forall.constraints` (after one-step superclass expansion) does
 //!   not include the residual class constraint. `ctx`:
 //!   `{"class": "<C>", "method": "<m>", "at_type": "<a>"}`. Concrete-
 //!   type residuals are deferred to the `no-instance` diagnostic.
-//! - `no-instance` (Iter 22b.2) — `severity: error`. Emitted by the
+//! - `no-instance` — `severity: error`. Emitted by the
 //!   per-fn typecheck arm when a class-method call resolves the class
 //!   param to a fully-concrete type that has no matching entry in the
 //!   workspace instance registry (`(class, canonical-type-hash)`).
 //!   Dual of `missing-constraint`: when the residual is concrete, the
 //!   fn cannot push the obligation to a caller, so an existing
 //!   instance is the only way to discharge it. `ctx`:
-//!   `{"class": "<C>", "method": "<m>", "at_type": "<T>"}`. mq.2 adds
-//!   an optional `candidate_classes` field when the residual originated
-//!   from the multi-candidate dispatch path; absent on single-class
-//!   residuals (back-compat).
-//! - `ambiguous-method-resolution` (mq.2) — `severity: error`. Emitted
+//!   `{"class": "<C>", "method": "<m>", "at_type": "<T>"}`. An
+//!   optional `candidate_classes` field is added when the residual
+//!   originated from the multi-candidate dispatch path; absent on
+//!   single-class residuals (back-compat).
+//! - `ambiguous-method-resolution` — `severity: error`. Emitted
 //!   by the type-driven dispatch resolver (or the discharge-time
 //!   multi-candidate refinement) when a bare-method call site survives
 //!   both type-driven and constraint-driven filtering with more than
 //!   one candidate class. `ctx`: `{"method": "<m>", "at_type": "<T>",
 //!   "candidate_classes": ["<C1>", ...]}`. The author disambiguates
 //!   by writing `<ClassQualifier>.<method> x`.
-//! - `unknown-class` (mq.2) — `severity: error`. Emitted by the
+//! - `unknown-class` — `severity: error`. Emitted by the
 //!   type-driven dispatch resolver when an explicit class qualifier
 //!   in a `Term::Var.name` (e.g. `"prelude.Show.show"`) names a
 //!   qualified class that is not in the workspace registry of
 //!   candidate classes for the method. `ctx`:
 //!   `{"name": "<qualified-class>"}`.
-//! - `class-method-shadowed-by-fn` (mq.3) — `severity: warning`.
+//! - `class-method-shadowed-by-fn` — `severity: warning`.
 //!   Emitted by `synth`'s `Term::Var` arm when a name resolves to a
 //!   free fn (locals / caller-module-fn / imported-fn) AND a class
 //!   method of the same name also exists in the workspace. Fn

crates/ailang-check/src/lift.rs

@@ -1,4 +1,4 @@
-//! Iter 16b.3: post-typecheck `Term::LetRec` lift.
+//! Post-typecheck `Term::LetRec` lift.
 //!
 //! Background. The 16a desugar pass (`ailang-core::desugar::desugar_module`)
 //! eliminates most `Term::LetRec` nodes by lifting them to synthetic

crates/ailang-check/src/linearity.rs

@@ -1,4 +1,4 @@
-//! Iter 18c.2: linearity check for fns whose every parameter mode is
+//! Linearity check for fns whose every parameter mode is
 //! explicit (`Borrow` or `Own`).
 //!
 //! ## Scope

crates/ailang-check/src/mono.rs

@@ -1,5 +1,5 @@
-//! Workspace monomorphisation pass (introduced iter 22b.3; the
-//! free-fn entry was added in iter 23.4).
+//! Workspace monomorphisation pass — class-method entry plus
+//! free-fn entry.
 //!
 //! Slots into the build pipeline after [`crate::lift_letrecs`] and
 //! before `ailang_codegen::lower_workspace_with_alloc`. It is only

crates/ailang-check/src/reuse_shape.rs

@@ -1,4 +1,4 @@
-//! Iter 18d.2: shape-compatibility check for `(reuse-as <var> <body>)`.
+//! Shape-compatibility check for `(reuse-as <var> <body>)`.
 //!
 //! ## Why this is its own pass
 //!

crates/ailang-check/src/suppress_filter.rs

@@ -1,4 +1,4 @@
-//! Iter 19b: per-module post-process that consumes
+//! Per-module post-process that consumes
 //! [`ailang_core::ast::FnDef::suppress`] entries.
 //!
 //! For each `Def::Fn(f)` and each `Suppress { code, because }` in

crates/ailang-check/src/uniqueness.rs

@@ -1,4 +1,4 @@
-//! Iter 18c.3: uniqueness inference over the typed AST.
+//! Uniqueness inference over the typed AST.
 //!
 //! This pass classifies every binder of every fn body as either
 //! [`Uniqueness::Unique`] or [`Uniqueness::Shared`]. Unlike the