Add Claude Code hooks and release skill

- PostToolUse hook: auto-format .rs files with rustfmt after edit
- PreToolUse hook: block direct edits to Cargo.lock
- /release skill: build .deb and inspect package metadata

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/skills/release/SKILL.md

@@ -0,0 +1,17 @@
+---
+name: release
+description: Build claudify .deb package and show build info
+disable-model-invocation: true
+---
+
+# Release
+
+Build the claudify .deb package and verify the output.
+
+## Steps
+
+1. Run `cargo tauri build` from the project root
+2. Show the build output path and file size
+3. Inspect the .deb package metadata with `dpkg-deb --info`
+4. List the .deb package contents with `dpkg-deb --contents`
+5. Report the package name, version, architecture, and installed size