fix(#1205): roadmapper applies phase_id_convention to generated phase IDs (#1215)

* fix(#1205): roadmapper applies phase_id_convention to generated phase IDs

- Add Phase ID Convention section to <phase_identification> block:
  documents sequential (default) vs milestone-prefixed forms, and
  instructs the agent to read phase_id_convention from config.json
- Update <output_formats> to show both header and checklist forms for
  sequential and milestone-prefixed conventions with examples
  (e.g. ### Phase 1-01: Name, - [ ] **Phase 1-01: Name**)
- Add TDD regression test tests/bug-1205-roadmapper-convention.test.cjs
  (5 assertions, confirmed fail-first then pass after fix)
- Update tests/agent-size-baseline.json to reflect legitimate growth
- Add .changeset/brave-otters-leap.md (Fixed, pr:0 placeholder)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* chore: backfill changeset pr: 1215 for fix/1205

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* test(#1205): move phase_id_convention regression into roadmapper-granularity.test.cjs

lint-regression-test-names rejects new standalone bug-NNNN-*.test.cjs files;
regression cases must live in the owning module's test file.

Move the 5 phase_id_convention assertions (#1205 regression) from the
removed tests/bug-1205-roadmapper-convention.test.cjs into
tests/roadmapper-granularity.test.cjs as a new describe block, alongside
the existing granularity calibration tests. Also update the allow-test-rule
comment to cover both #163 and #1205 surface contracts.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* test(#1205): fix lint-allow-test-rule-refs for roadmapper-granularity

- Add issue ref (see #1205) to allow-test-rule comment in
  tests/roadmapper-granularity.test.cjs so lint-allow-test-rule-refs
  passes (new exemptions require #NNN per ADR-456)
- Prune stale 'source-text-is-the-product' entry from
  scripts/lint-allow-test-rule-refs.allowlist.json (ratchet-down;
  comment now compliant and no longer needs grandfathering)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/lint-allow-test-rule-refs.allowlist.json

@@ -291,7 +291,6 @@
   "tests/research-agent-profiles.test.cjs :: <runtime-contract-is-the-product> research agent .md content is the governed surface",
   "tests/review-default-reviewers-workflow.test.cjs :: source-text-is-the-product",
   "tests/roadmap.test.cjs :: source-text-is-the-product",
-  "tests/roadmapper-granularity.test.cjs :: source-text-is-the-product",
   "tests/run-tests-harness.test.cjs :: run-tests.cjs is a CLI test harness whose only IR is its",
   "tests/runtime-launcher-parity.test.cjs :: structural parity/drift guard — asserts literal presence/absence of the canonical gsd_run launcher and the retired $GSD_SDK / `/gsd-tools` tokens across workflow markdown; there is no typed IR for \"this source file does not contain substring X\".",
   "tests/runtime-name-policy.test.cjs :: runtime-contract-is-the-product — FALLBACK_ALIASES source text IS the",