chore: add Claude Code project config, git hooks, and session setup

- CLAUDE.md (root + Server + client) documenting commands, generated-code
  rules, and the known-red client unit suite policy
- .claude/skills: ci-check (local CI mirror), protocol-change, db-change
  workflows for the sqlc/protocol codegen invariants CI enforces
- .githooks pre-commit/pre-push mirroring CI's fast gates (gofmt, go vet,
  oxlint, prettier, tsc, tag-variant builds, sqlc/protocol staleness),
  enabled via 'npm run hooks:install'
- .claude SessionStart hook installing client npm deps and warming the Go
  module cache so remote sessions can run tests/linters immediately
- .mcp.json with Playwright and Context7 MCP servers
- .gitignore: commit shared Claude config; keep local-only overrides ignored

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BDcVJqGjHcJVLoV4x1HFjW

package.json

@@ -2,7 +2,8 @@
   "private": true,
   "scripts": {
     "changelog": "changelogen",
-    "release": "changelogen --release"
+    "release": "changelogen --release",
+    "hooks:install": "git config core.hooksPath .githooks"
   },
   "devDependencies": {
     "changelogen": "^0.6.2"