roadmap: introduce docs/roadmap.md as forward queue

Adds a priority-ordered, checkbox-format roadmap that the
orchestrator maintains. Three states (`[ ]` open / `[~]` in
progress / `[x]` done), four kinds (milestone / feature / todo /
idea), four priorities (P0..P3). Initial population lifts the
queued items from the JOURNAL tail.

JOURNAL's role narrows: chronological decisions log only, no
forward queue. CLAUDE.md "Roles of ..." section updated to
reflect the split.

docs/roadmap.md

@@ -0,0 +1,108 @@
+# AILang Roadmap
+
+Priority-ordered list of upcoming work — milestones, features, todos,
+and ideas. The orchestrator maintains this file. The user can request
+additions; the orchestrator chooses what to remove or reprioritise as
+work progresses.
+
+## Conventions
+
+- One checkbox per entry. `- [ ]` is open; `- [~]` is in progress
+  (work has started — a plan exists, a branch is open, or commits are
+  landing); `- [x]` is done. A finished entry may stay briefly for
+  context, then is removed (with a one-line mirror in
+  `docs/JOURNAL.md`).
+- Each entry is tagged by **kind** and lives under a **priority**
+  bucket:
+  - **\[milestone\]** — big chunk that will get a `docs/specs/<milestone>.md`.
+  - **\[feature\]** — smaller addition inside a milestone, no full
+    spec.
+  - **\[todo\]** — concrete task that can run without a brainstorm
+    (cleanup, doc fix, mechanical refactor, test backfill).
+  - **\[idea\]** — not yet decision-ready, no commitment.
+- Optional `depends on:` line names another entry that has to land
+  first.
+- Optional `context:` line points to the JOURNAL entry where the
+  rationale lives. The roadmap is intentionally terse; rationale
+  stays in JOURNAL.
+- Priority buckets:
+  - **P0** — in flight. Spec or plan already exists.
+  - **P1** — next up. Decision made; not yet started.
+  - **P2** — medium-term. Decided in principle, scheduled later.
+  - **P3** — ideas. No commitment; may be cut.
+
+## P0 — In flight
+
+- [~] **\[milestone\]** design-md-consolidation — `docs/DESIGN.md`
+  becomes a state-only specification across four thematic sweeps
+  (history anchors out, migration plans out, schema-SoT inversion +
+  data-model hardening, workflow / cross-reference cleanup).
+  - context: `docs/specs/2026-05-10-design-md-consolidation.md`
+  - sub-entries:
+    - [~] Sweep 1 — remove history anchors
+      (`docs/plans/2026-05-10-design-md-consolidation-1-history-anchors.md`;
+      tasks 1-3 of 6 landed)
+    - [ ] Sweep 2 — REVERTED + migration plans out
+    - [ ] Sweep 3 — schema SoT inversion + data-model hardening
+    - [ ] Sweep 4 — workflow / cross-reference cleanup
+
+## P1 — Next
+
+- [ ] **\[milestone\]** Post-22 Prelude — ship `Show` / `Eq` / `Ord`
+  with the four primitive instances (Int, Bool, Str, Float); rewire
+  `print` through `Show.show`. Originally queued as 22b.4 in the
+  typeclass milestone, kept on hold pending demand.
+  - context: JOURNAL 2026-05-09 ("JOURNAL queue")
+  - depends on: design-md-consolidation (touches DESIGN.md schema
+    sections that the consolidation will reshape)
+
+## P2 — Medium-term
+
+- [ ] **\[feature\]** Operator routing through `Eq` / `Ord` — `==`,
+  `<` etc. resolved via the typeclass instead of the built-in
+  primitive comparators. No commitment; gated on bench re-baselining
+  to make sure the indirection doesn't tank latency.
+  - context: JOURNAL 2026-05-09
+  - depends on: Post-22 Prelude
+- [ ] **\[todo\]** `types` / `ctor_index` overlay shape question —
+  decide whether the env's two parallel ctor maps should collapse
+  into one overlay, or stay split. Surfaced during the
+  env-construction unify audit.
+  - context: JOURNAL 2026-05-10 ("Audit close: env-construction unify")
+- [ ] **\[feature\]** 22c — typeclass corpus expansion. User-defined
+  classes beyond the prelude four; multi-parameter classes; superclass
+  chains; richer instance bodies. Deferred from milestone 22.
+  - context: JOURNAL 2026-05-09
+- [ ] **\[todo\]** Boehm full retirement — remove the transitional
+  Boehm GC path now that RC + uniqueness is the canonical memory
+  story.
+  - context: JOURNAL pre-22, "Boehm transitional"
+- [ ] **\[feature\]** Closure-pair slab / pool — codegen tweak to
+  pool the env+code closure pairs instead of one-shot heap allocs.
+  Bench-gated.
+- [ ] **\[todo\]** `FnDef::synthetic` flag — formalise the
+  monomorphiser-emitted FnDefs so downstream passes can tell
+  user-authored from synthesised at a glance. Currently inferred from
+  symbol naming.
+- [ ] **\[todo\]** 21'h iteration — final 21' carry-over (latency
+  methodology pass). Numbering kept for continuity with the 21' arc.
+
+## P3 — Ideas
+
+- [ ] **\[idea\]** Latency methodology rework — switch from per-run
+  timing to a histogram-based approach so tail-latency regressions
+  are visible without re-running. Queued from 21'g.
+- [ ] **\[idea\]** Parser-test backfill for 22b.4a-era duplicate-clause
+  sites (class × 3, class method × 2, instance × 3, instance method
+  × 1). No regression pin today; only worth it if a 22b.4a-era
+  diagnostic needs to change.
+  - context: JOURNAL 2026-05-10 ("Iteration 22-tidy.7")
+- [ ] **\[idea\]** `write_type` `Type::Forall` arm in
+  `crates/ailang-prose/src/lib.rs` silently drops constraints in
+  inline-type rendering. Dormant — surface forms today only carry
+  forall at fn-signature top level. Fix only if a future feature
+  carries forall + constraints inline.
+  - context: JOURNAL 2026-05-10 ("Iteration 22-tidy.6")
+- [ ] **\[idea\]** Richer integration paths between RC and
+  uniqueness — deferred from the 21' arc; revisit once the
+  uniqueness inference covers more program shapes.