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/hooks/block-cargo-lock.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+# Block direct edits to Cargo.lock — it should only change via cargo
+INPUT=$(cat)
+FILE_PATH=$(echo "$INPUT" | jq -r '.tool_input.file_path // empty')
+
+if [[ "$FILE_PATH" == *"Cargo.lock" ]]; then
+    echo '{
+        "hookSpecificOutput": {
+            "hookEventName": "PreToolUse",
+            "permissionDecision": "deny",
+            "permissionDecisionReason": "Cargo.lock is auto-generated. Use cargo to update dependencies."
+        }
+    }'
+else
+    exit 0
+fi