docs: add code ownership rules

.github/CODEOWNERS

@@ -0,0 +1,35 @@
+# Default owner for all changes.
+* @lanmu1818-ship-it
+
+# Repository governance and release safety.
+/.github/ @lanmu1818-ship-it
+/SECURITY.md @lanmu1818-ship-it
+/CONTRIBUTING.md @lanmu1818-ship-it
+/README.md @lanmu1818-ship-it
+/docs/release-readiness.md @lanmu1818-ship-it
+/docs/operations.md @lanmu1818-ship-it
+/docs/deployment.md @lanmu1818-ship-it
+
+# Core application surfaces.
+/app/(admin)/settings/ @lanmu1818-ship-it
+/app/(chat)/api/chat/ @lanmu1818-ship-it
+/app/api/canvas/ @lanmu1818-ship-it
+/components/canvas/ @lanmu1818-ship-it
+/components/home/ @lanmu1818-ship-it
+
+# Infrastructure, security, and data boundaries.
+/lib/observability/ @lanmu1818-ship-it
+/lib/security/ @lanmu1818-ship-it
+/lib/storage/ @lanmu1818-ship-it
+/lib/db/ @lanmu1818-ship-it
+/lib/ai/ @lanmu1818-ship-it
+/scripts/check-*.mjs @lanmu1818-ship-it
+/scripts/check-*.ts @lanmu1818-ship-it
+/scripts/security/ @lanmu1818-ship-it
+
+# Quality gates and dependency manifests.
+/package.json @lanmu1818-ship-it
+/pnpm-lock.yaml @lanmu1818-ship-it
+/tsconfig.json @lanmu1818-ship-it
+/next.config.ts @lanmu1818-ship-it
+/biome.jsonc @lanmu1818-ship-it

CONTRIBUTING.md

@@ -56,6 +56,8 @@ Use the PR template and include:
 - Verification output or screenshots when relevant.
 - Any intentional follow-up work.
 
+CODEOWNERS is configured for governance, security, CI, settings, Canvas, API, and infrastructure paths. If your PR touches those areas, expect owner review before merge.
+
 For frontend changes, include screenshots or a short visual verification note. For route/API changes, include status codes, response-shape notes, or targeted test evidence.
 
 ## Security