feat(lint): add no-unused-vars ratchet scoped to src+open-sse+tests

[maxmad64bis]

⚠️ base-red inherited: #9985

Summary

Unused variables are currently invisible in this repo. No rule watches them, so they don't show up in the ratchet drift either — every release cycle quietly accumulates a few more: parameters left behind by refactors, catch clauses that drop the error, destructuring that grabs more than it uses. Nobody writes them on purpose, and individually they're harmless. The problem is cumulative: after a while readers can't tell which parameters are actually part of a function's contract, and an unused parameter is often the fingerprint of a call path that no longer works the way its signature suggests.

This PR doesn't fix any of them and doesn't ask anyone to. It just extends the mechanism the repo already trusts — bulk suppressions with a hard wall for new code — to the last big category of lint debt that has no gate. Everything frozen today stays frozen; from the next commit on, a new unused binding fails lint inside the PR that introduced it, where fixing it costs seconds and the author still remembers why it was there. The escape hatch is deliberately generous: prefix it with _ and the linter stays out of your way.

Concretely:

• @typescript-eslint/no-unused-vars scoped to src/, open-sse/ and tests/ — the same directories the existing scoped rules target; scripts/, bin/ and docs/ stay out of scope.
• The 1393 pre-existing violations are frozen in bulk via config/quality/eslint-suppressions.json, same pattern as the toNumber restriction from refactor(quality): 51 definições divergentes de toNumber espalhadas por src/ e open-sse/ — consolidar em helpers canônicos com testes #7879.
• Also untracks two docs/superpowers/* planning files that entered the tree with feat: guide Qdrant memory configuration #11213 while being gitignored; their presence currently makes the tracked-artifacts pre-commit hook reject every new commit on this branch, for every contributor.
• Changelog fragment under changelog.d/maintenance/ (renamed to the real PR number once known).

Related Issues

• Refs 🔴 Release branch not green: release/v3.8.50 #9985 (base not green — this PR does not fix it, see Reviewer Notes)
• Follows the precedent of refactor(quality): 51 definições divergentes de toNumber espalhadas por src/ e open-sse/ — consolidar em helpers canônicos com testes #7879 (freeze-then-ratchet)

Validation

Choose the change type and focused loop from the
Contribution Golden Path. The full unit suite,
Vitest, the 60% coverage gate, and the production build all run in CI on this PR (#8329):

• Change type: other (lint tooling / quality gate)
• Focused tests and category gates from the golden path
• npm run lint
• Reconciled with the current active release base; focused checks rerun afterward
• Production-code changes include a new or updated automated test in this PR
• SonarQube is temporarily opt-in while the private project has no quota; it is not a PR gate.

Tests Added Or Updated

• No production code changed — config (eslint.config.mjs) and suppressions data only, so no new test file is added. The ratchet behavior was verified with throwaway probe files (removed): a new unused variable in src/ fails lint, a leading unused parameter is still flagged (args: "all"), and scripts/*.mjs remains ignored.

Coverage Notes

• No src/, open-sse/, electron/ or bin/ runtime code is touched by the rule itself; the only tracked-file deletions are the two leaked planning docs. Coverage is unaffected.

Reviewer Notes

• The bulk-suppressions JSON was produced by ESLint's native --suppress-rule + --suppressions-location mechanism (the same one wired into npm run lint and lint-staged — see package.json:109 and :411). The exact command to reproduce / refresh the file from the current base is:

  npx eslint --fix --no-error-on-unmatched-pattern --no-warn-ignored \
    --suppress-rule "@typescript-eslint/no-unused-vars" \
    --suppressions-location config/quality/eslint-suppressions.json \
    'src/**/*.{ts,tsx,js,jsx}' 'open-sse/**/*.ts' 'tests/**/*.{ts,tsx,mjs}'
  

  Output is keyed by file path; each entry holds { "@typescript-eslint/no-unused-vars": { "count": N } }. The -455 lines in this diff are the --prune-suppressions half of the same run — entries that no longer occur on the current tip. The freeze count (1393) covers args, vars and catch clauses together across all three scopes, which is why it's higher than a spot-check would suggest. One ESLint pass over the three scoped globs takes ~3 min on a warm cache.

• docs/superpowers/ is gitignored on release/v3.8.50 (/.gitignore:169), so the two files leaked via feat: guide Qdrant memory configuration #11213 are an isolated slip, not an ongoing drift. This PR git rms them so the tracked-artifacts pre-commit hook stops rejecting every new commit on the branch. The untrack is kept in this PR rather than split out because (a) it is the symptom of the same merge (feat: guide Qdrant memory configuration #11213) that also brings the ~20 unsuppressed no-explicit-any mentioned below, and (b) splitting would force PR-A to merge before PR-B or risk the hook rejecting PR-A's own commits. Happy to split on maintainer request.

• On top of the inherited base-red (🔴 Release branch not green: release/v3.8.50 #9985), the current tip also carries ~20 unsuppressed no-explicit-any in tests/integration/qdrant-routes.test.ts (arrived with feat: guide Qdrant memory configuration #11213). Pre-existing and untouched here.