openapi: entire /v1/lint/* + /v1/validate/focus-manifest family (8 routes) missing from spec

[JSONbored]

⚠️ Definition of Done: this issue must be completed in full, in a single PR. Do not split this
work across multiple PRs, and do not defer any Deliverable below to a follow-up issue. A PR that
satisfies only some of the Deliverables, stubs a required test, or leaves a checkbox
partially-done does NOT resolve this issue and will be closed.

⚠️ Required pattern: mirror how GET /v1/repos/{owner}/{repo}/gate-config/effective is documented
in src/openapi/spec.ts — issue #6611 fixed the exact same class of gap for that route — applied
uniformly across all eight routes below.

Context

src/api/routes.ts groups eight deterministic, source-free advisory-check POST routes under
/v1/lint/* and /v1/validate/focus-manifest, each backed by an MCP tool with its own Zod output
shape already defined in src/mcp/server.ts:

Route	MCP tool	Output shape
POST /v1/lint/pr-text	loopover_lint_pr_text	lintPrTextOutputSchema
POST /v1/lint/slop-risk	loopover_check_slop_risk	checkSlopRiskOutputSchema
POST /v1/lint/improvement-potential	loopover_check_improvement_potential	checkImprovementPotentialOutputSchema
POST /v1/lint/open-pr-pressure	loopover_simulate_open_pr_pressure	simulateOpenPrPressureOutputSchema
POST /v1/lint/boundary-tests	loopover_suggest_boundary_tests	suggestBoundaryTestsOutputSchema
POST /v1/lint/test-evidence	loopover_check_test_evidence	checkTestEvidenceOutputSchema
POST /v1/lint/issue-slop	loopover_check_issue_slop	checkIssueSlopOutputSchema
POST /v1/validate/focus-manifest	loopover_validate_config	validateConfigOutputSchema

None of the eight appears in src/openapi/spec.ts — grep for /v1/lint/ and
/v1/validate/focus-manifest in that file returns nothing, even though every one of them is a real,
tested, publicly-callable route with an MCP-tool-validated response shape.

Requirements

• In src/openapi/schemas.ts, define one z.object({...}) response schema per route (8 total,
  e.g. LintPrTextResponseSchema, CheckSlopRiskResponseSchema,
  CheckImprovementPotentialResponseSchema, SimulateOpenPrPressureResponseSchema,
  SuggestBoundaryTestsResponseSchema, CheckTestEvidenceResponseSchema,
  CheckIssueSlopResponseSchema, ValidateFocusManifestResponseSchema), using each route's
  existing MCP outputSchema constant (table above) as the field-level source of truth. Also add
  request-body schemas mirroring each tool's corresponding inputSchema/shape constant in
  src/mcp/server.ts.
• In src/openapi/spec.ts, registry.register all eight response schemas as components, then add a
  registerPath entry for each of the eight routes.
• Schema is the contract — regenerate and commit. Run npm run ui:openapi after the edits and
  commit the regenerated apps/loopover-ui/public/openapi.json in this same PR. CI enforces this via
  npm run ui:openapi:check (part of npm run test:ci).

Deliverables

• Eight new response schemas (plus matching request-body schemas) added to
  src/openapi/schemas.ts, one per route in the table above.
• All eight routes registered as OpenAPI paths in src/openapi/spec.ts.
• apps/loopover-ui/public/openapi.json regenerated via npm run ui:openapi and committed.
• npm run ui:openapi:check passes in CI.

All eight routes are required in this one PR — there is no follow-up issue. Do not ship a partial
subset of the family.

Test Coverage Requirements

99%+ Codecov patch target (codecov/patch, unsharded via npm run test:coverage) on any new schema
helper code. Add a regression test asserting all eight paths appear in buildOpenApiSpec()'s output
with response schemas whose keys match each route's MCP tool output shape from the table above.

Expected Outcome

The entire /v1/lint/* + /v1/validate/focus-manifest advisory-check family is documented in
GET /openapi.json / apps/loopover-ui/public/openapi.json, matching what each route's MCP tool
already validates.

Links & Resources

• src/api/routes.ts: the eight routes in the table above (contiguous block starting at
  app.post("/v1/lint/pr-text", ...))
• src/mcp/server.ts: the eight output-shape constants in the table above (contiguous block of
  register("loopover_lint_pr_text"...) through register("loopover_check_issue_slop"...) /
  register("loopover_validate_config"...))
• src/openapi/spec.ts: /v1/repos/{owner}/{repo}/gate-config/effective registration (pattern to
  mirror)
• OpenAPI spec is missing GET /v1/repos/{owner}/{repo}/gate-config/effective (documented sibling: live-gate-thresholds) #6611 — the precedent issue for this exact class of gap

[linear-code]

JSO-6463