kicad-validity B3+C+S: revert toast, corpus lint, .kicad_mod tier

B3 (editor): kicad-binding observes kdoc_meta.revertNonce (deduped, like
seedNonce) → DOC_REVERTED_EVENT → WasmTool doc-reverted-toast (15 s,
data-testid for the deferred e2e check).
C: tests/tools/corpus-lint.ts (npm run corpus:lint) — kicad_tools --lint
over the fixture corpora raw + shared-codec round-trips
(docToFile(fileToDoc(x))); the E3/wrapInBoardEnvelope-class gate. Skips
when output/kicad_tools.js isn't built; CI step lands when kicad_tools
joins the CI app set. 7 fixtures / 7 round-trips green.
S: --lint + --resave gain the .kicad_mod tier (pcbToolsLintFootprint /
pcbToolsResaveFootprint; writer needs CTL_FOR_LIBRARY or the board flags
strip the (version) header). Verified: qa footprint round-trip lints
clean, resave stamps 20260206, garbage exits 1. Also bumps pcbjam-shared
(mergeYUpdates for the bisect pass).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HLua64PCVwkQ1hpWdaf1Gm

tests/package.json

@@ -44,6 +44,7 @@
     "test:asyncify:chrome": "playwright test --config=playwright-asyncify.config.ts --project=chromium --headed",
     "test:asyncify:safari": "playwright test --config=playwright-asyncify.config.ts --project=webkit",
     "test:asyncify:all": "npm run test:asyncify:firefox && npm run test:asyncify:safari && npm run test:asyncify:chrome",
+    "corpus:lint": "tsx tools/corpus-lint.ts",
     "lint:determinism": "tsx tools/lint-determinism.ts",
     "screenshots:check": "tsx tools/screenshots/compare.ts",
     "screenshots:promote": "tsx tools/screenshots/promote.ts",