Test infrastructure release.

Test infrastructure release. Closes the two follow-ons documented in 1.5.5 and 1.5.6 CHANGELOGs as the structural drift-prevention against the class of bug that produced both hotfixes (FIRST_PARTY_ADAPTERS divergence + bundle-vs-source CI gap).

Daemon code unchanged — 1.5.0 48 h soak verdict applies to 1.5.7.

Added

• first-party-adapters-coverage.test.ts — strict drift-guard asserting FIRST_PARTY_ADAPTERS (the runtime dispatch list at codebase-introspector.ts:75-78) parity with CORE_BUNDLED_IDS (the trust-class id-set at detect/adapters/index.ts:23-33). Pre-1.5.7 the two diverged silently — Phase 7 commits added each new adapter to CORE_BUNDLED_IDS (gated by core-bundled-ids-drift.test.ts) but missed the runtime dispatch list. The 1.5.4 → 1.5.5 hotfix was the surfacing event. This test makes the divergence impossible to merge: every id in CORE_BUNDLED_IDS must have an adapter import in codebase-introspector.ts AND vice versa.
• CI tarball-e2e job — extends .github/workflows/ci.yml with a job that runs MASSU_TARBALL_E2E=1 npx vitest run src/tests/init-tarball-e2e.test.ts on every push to main + PR. The test infrastructure was added in 1.5.3 but had no CI trigger; 1.5.5 and 1.5.6 both shipped bundle-only bugs (FIRST_PARTY_ADAPTERS omission, web-tree-sitter not externalized) that the tarball-e2e gate would have caught BEFORE publish if it had been wired. Now wired; future bundle-vs-source regressions auto-fail CI before publish.

Verification

• npx tsc --noEmit: 0 errors
• npm test: 2087/2087 source-level pass (+1 new drift test)
• bash scripts/massu-pattern-scanner.sh: PASS
• bash scripts/massu-generalization-scanner.sh: PASS

Closes

• Plan 1.5.5 CHANGELOG follow-on ("first-party-adapters-coverage gate") — SHIPPED.
• Plan 1.5.6 CHANGELOG follow-on ("CI workflow that sets MASSU_TARBALL_E2E=1") — SHIPPED.