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).

design/models/rc-uniqueness.md

@@ -1,6 +1,6 @@
 # RC + Uniqueness — memory model whitepaper
 
-## Decision 9: dual allocator — RC canonical, Boehm parity oracle
+## Dual allocator — RC canonical, Boehm parity oracle
 
 AILang ships two allocator backends with an asymmetric role:
 
@@ -25,12 +25,11 @@ when the parity oracle stops paying its keep — concretely, when a
 few iter families ship without the gc arm catching anything that
 the rc arm did not already catch. Until then, the cost of
 keeping libgc as a build dependency is accepted in exchange for
-diagnostic leverage. Decision 10 (RC + uniqueness) holds as the
-specification of the canonical runtime (the contract version is
-[memory model](../contracts/memory-model.md), built on
-[language constraints](../contracts/language-constraints.md));
-the rest of this section documents the Boehm half, retained as
-the oracle.
+diagnostic leverage. The
+[RC + uniqueness memory model](../contracts/memory-model.md), built
+on the [language constraints](../contracts/language-constraints.md),
+holds as the specification of the canonical runtime; the rest of
+this section documents the Boehm half, retained as the oracle.
 
 **Choice: Boehm-Demers-Weiser conservative GC.** The simplest
 working option:
@@ -130,7 +129,7 @@ The closure-pair and its env share an escape verdict — they have
 parallel lifetimes. If the closure pair is non-escaping, the env
 is too.
 
-## Decision 10: memory model — RC + Uniqueness with LLM-author annotations
+## Memory model — RC + Uniqueness with LLM-author annotations
 
 **The GC bench (`bench/run.sh`) showed
 Boehm contributing a substantial fraction of runtime on allocation-heavy workloads
@@ -150,9 +149,10 @@ stdlib is the cheapest moment to commit.
 **Choice.** AILang's canonical [memory model](../contracts/memory-model.md)
 is reference counting with static uniqueness inference **and
 explicit LLM-author annotations on fn signatures**, in the lineage
-of Lean 4 / Roc / Koka. Boehm becomes a transitional allocator (Decision 9) and is
-retired when the RC pipeline matches the bump-allocator floor
-within an acceptable margin (target 1.3× on `bench/run.sh`).
+of Lean 4 / Roc / Koka. Boehm becomes a transitional allocator (see
+the dual-allocator section above) and is retired when the RC pipeline
+matches the bump-allocator floor within an acceptable margin (target
+1.3× on `bench/run.sh`).
 
 **Workload scope of the 1.3× target.** The 1.3× target was
 calibrated on the original `bench/run.sh` corpus: linear list
@@ -168,16 +168,17 @@ one bump-pointer bump, doubling the allocation tax on closure
 construction (current ratio recorded in JOURNAL bench entries).
 This is a representational cost of the closure-pair layout,
 not a defect in the RC implementation; a future slab/pool
-allocator for fixed-shape pair cells (Decision 9 retirement
-follow-up) would compress this ratio without changing semantics.
+allocator for fixed-shape pair cells (a Boehm-retirement follow-up)
+would compress this ratio without changing semantics.
 
 The 1.3× retirement target therefore applies to the linear /
 tree / poly-ADT subset of the corpus. Closure-heavy workloads are
 tracked under a wider band (the closure-chain baseline records its rc/bump ratio as the `rc_over_bump` reference value with ±15% tolerance) and
 are explicitly excluded from the Boehm-retirement gate until a
-slab/pool answer ships. Decision-10's RC commitment is unchanged;
-what is scoped is the *quantitative* retirement criterion, not
-the choice of memory model.
+slab/pool answer ships. The
+[memory model](../contracts/memory-model.md)'s RC commitment is
+unchanged; what is scoped is the *quantitative* retirement criterion,
+not the choice of memory model.
 
 The architecture has two layers: