chore(quality): remove unreachable code and restore test discovery

[backryun]

Summary

• remove 48 verified unreachable files across detached dashboard UI, superseded quota components, unused docs/Storybook components, stale helpers, and unused OAuth CLI presentation utilities
• remove two obsolete tests that did not exercise current production behavior
• move the memory settings API test into the discovered Vitest tree, update it for the current response contract, and import the owning DB module directly
• add the translator test directory to the Node unit collectors, merge-train fast path, and impacted-test selector
• remove stale ESLint suppressions for deleted or already-clean files
• keep documented runtime error codes distinguishable from environment variables after removing the unused API response constants module
• tighten tracked quality debt: dead-code total 408 -> 360 and frozen test-discovery orphans 13 -> 10

This intentionally stops at static-analysis boundaries: dynamic plugin/worker/vendor entrypoints, side-effect barrels, OneProxy contracts, and tool-policy contracts are left untouched for separate review.

Validation

• npm run test:vitest — 50 files, 459 tests passed
• npm run typecheck:core
• npm run check:cycles
• npm run check:dead-code — 331 unused exports + 29 unused files = 360
• npm run check:test-discovery — 5261 test files, 32 collectors, 10 frozen orphans
• fabricated-docs and release-green docs regressions — 28 passed
• npm run check:docs-all — passed
• focused merge-train and impacted-test regressions — 25 passed
• changed-file ESLint with the repository suppression config — passed with zero warnings
• pre-commit lint-staged and repository policy hooks — passed
• git diff --check

Known inherited gate failures

• full lint:json currently depends on chore(quality): re-freeze the ESLint suppressions on release/v3.8.51 from a clean-room run #11955, which freezes 55 pre-existing no-explicit-any violations and removes the unused GPT_SIZE_MAP
• unit shard 3/4 currently depends on chore(release): sync main into release/v3.8.51 — the four post-release CI/publish commits #11957, which fixes the base test import in tests/unit/openai-to-claude-trailing-usage-deferred-finish.test.ts
• hosted Fast Production Build and dast-smoke OOM/cancellation are tracked by ci: Fast Production Build + dast-smoke (hosted 7 GB) OOM on release/v3.8.51 — 19/30 red, paints every PR #11946

No runtime behavior change is intended; the production-code portion is deletion of unreachable modules plus a direct import from the existing settings DB module.

[diegosouzapw]

Marcando para o ciclo v3.8.52. Deleta 48 arquivos ("unreachable code") — CONFLICTING no momento, e o próprio corpo lista dependências em duas outras PRs ainda não mergeadas (#11955, #11957) para os gates completos passarem. Deleção grande demais para validar em lote; merece sessão dedicada para confirmar cada arquivo removido não tem consumidor remanescente.

[diegosouzapw]

Validated in local merge-train on 192.168.0.113 — train of #12258 #12262 #12166 #12281 #11259 #11950 merged clean onto origin/release/v3.8.51 (f5e7095):

• Run 1 (/opt/actions-runner-omniroute-5, train tip 85cd9119): typecheck:core, file-size, complexity ×2, changelog-integrity — all green; the test:unit step was killed by a CI job landing on that runner mid-train (workspace clobbered — infra, documented risk).
• Run 2 (/srv/omniroute-train/.claude/worktrees/mt-green1, same 6 PRs re-boarded, fresh npm ci): unit 35768/35805 pass (/tmp/mt-unit2.log), vitest 464/465 (/tmp/mt-vitest2.log).
• Every failure is a latency/timing assert (bounded-time, event-loop lag, cooldown windows) on a box that was never idle (3 active CI runner workers throughout). Discriminated per merge-gates §3: the 3 persistent titles reproduce identically on the pure base tip on the same box (/tmp/mt-base-isolated.log, BASE_ISOLATED_EXIT=1 — same tests, same asserts), 5 more titles reproduce on the pure base on the devbox, and the single vitest failure (provider-family-combos) also fails on main's nightly without any of these PRs. Inherited/infra — not introduced by this train.