Stop tracking .env and restore the ignore rules that 3455ad0 removed

3455ad0 deleted the .env patterns from .gitignore and committed a
real .env carrying a live ANTHROPIC_API_KEY. Two problems:

  - The key is now in shared history and must be rotated; untracking
    the file here stops the bleeding but does not un-publish it.
  - That .env does not boot the API. It sets ANTHROPIC_API_KEY with no
    MODEL_API_KEY, which config.go:503 refuses at startup — the same
    guard that crash-looped krow-2 on 2026-09-07. Nothing in the
    codebase reads ANTHROPIC_API_KEY; the MCP surface needs
    OAUTH_ISSUER and MCP_RESOURCE, not a model credential.

The file stays on disk and is ignored again, along with
infrastructure/.env which the deleted pattern also covered.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PJvibeSc1JYXjatankqM1g

.gitignore

@@ -1,5 +1,8 @@
 # Secrets and local configuration
 # A bare pattern matches at any depth, so this covers infrastructure/.env too.
+.env
+.env.local
+.env.*.local
 
 # TLS material. The local-db overlay generates a self-signed pair inside the
 # postgres volume, but nothing stops someone dropping certs here by hand.