feat(git-flow): add commit message enforcement hook (#225)

Implements PreToolUse/Bash hook to validate conventional commit format:
- Validates type(scope): description format
- Supports all 10 types: feat, fix, docs, style, refactor, perf, test, chore, build, ci
- Optional scope support
- Helpful error messages with examples
- Non-commit commands pass through
- Uses Python for reliable JSON parsing

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/git-flow/hooks/hooks.json

@@ -0,0 +1,19 @@
+{
+  "hooks": {
+    "PreToolUse": [
+      {
+        "matcher": "Bash",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "${CLAUDE_PLUGIN_ROOT}/hooks/branch-check.sh"
+          },
+          {
+            "type": "command",
+            "command": "${CLAUDE_PLUGIN_ROOT}/hooks/commit-msg-check.sh"
+          }
+        ]
+      }
+    ]
+  }
+}