gitignore: SQLite WAL runtime + local docs/specs dirs

*.db-shm / *.db-wal show up in the working tree whenever the server
runs (the WAL/journal pragmas in connect()), and /docs and /specs
hold per-feature design notes that stay local per the project's
"spec docs not in git" convention.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -2,8 +2,12 @@
 database/target
 *.db
 *.db.bak
+*.db-shm
+*.db-wal
 .env
 /tmp
+/docs
+/specs
 
 # Default ignored files
 .idea/shelf/