chore(harness): make repository agent-ready

Add concise routed context, task-aware agent roles, focused skills, and structured learning promotion.\n\nUnify local development and workspace tooling, add layered test and E2E verification, harden MCP authentication, and gate deployment behind verification and explicit production promotion.

apps/mcp/AGENTS.md

@@ -0,0 +1,11 @@
+# Internal MCP service
+
+Hono service exposing privileged administrative tools.
+
+- Treat the service-role key and `SAUCI_MCP_API_KEY` as secrets.
+- Fail closed when MCP authentication is missing outside explicit local mode.
+- Every mutation validates inputs, authorizes the operation, and writes audit
+  evidence where the product contract requires it.
+- Read operations preserve least privilege and avoid excessive user data.
+- Add unit/API coverage for tool contract or auth changes.
+- Verify lint, tests, typecheck, build, and `/health` locally.