chore: add ruff formatter, .gitignore, and uv convention (#40)

* chore: add ruff formatter, .gitignore, and uv convention

- Add ruff as dev dependency with basic config
- Add PostToolUse hook to auto-run ruff on .py edits
- Create .gitignore to exclude __pycache__ and settings.local.json
- Document uv run convention in CLAUDE.md
- Add CLAUDE.md, .claude/settings.json, and skills
- Apply ruff formatting to existing Python files

* fix: address CR feedback on hooks and uv run convention

- Fix hooks to read file_path from stdin JSON via jq instead of
  nonexistent $CLAUDE_FILE env var
- Update CLAUDE.md commands to use uv run python3 consistently
- Update skills to use uv run for python/dedup commands

.claude/settings.json

@@ -0,0 +1,71 @@
+{
+  "hooks": {
+    "PreToolUse": [
+      {
+        "matcher": "Edit|Write",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "file=$(jq -r '.tool_input.file_path // empty'); if [[ \"$file\" == *README.md || \"$file\" == *index.html ]]; then echo 'BLOCKED: README.md and index.html are generated artifacts. Edit create_listing.py instead, then run /regen-listings.' >&2; exit 2; fi"
+          }
+        ]
+      },
+      {
+        "matcher": "Edit|Write",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "file=$(jq -r '.tool_input.file_path // empty'); if [[ \"$file\" == */uv.lock || \"$file\" == uv.lock ]]; then echo 'BLOCKED: uv.lock is auto-generated. Modify pyproject.toml and run uv sync instead.' >&2; exit 2; fi"
+          }
+        ]
+      },
+      {
+        "matcher": "Edit|Write",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "file=$(jq -r '.tool_input.file_path // empty'); if [[ \"$file\" == *.github/workflows/*.yml || \"$file\" == .github/workflows/*.yml ]]; then echo 'BLOCKED: CI workflows use pinned action SHAs with # version comments for security. Edit workflow files carefully and maintain the SHA-pinning convention.' >&2; exit 2; fi"
+          }
+        ]
+      },
+      {
+        "matcher": "Edit|Write",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "file=$(jq -r '.tool_input.file_path // empty'); if [[ \"$file\" == */renovate.json || \"$file\" == renovate.json ]]; then echo 'BLOCKED: renovate.json is rarely edited. Make changes deliberately and confirm with the user first.' >&2; exit 2; fi"
+          }
+        ]
+      },
+      {
+        "matcher": "Edit|Write",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "file=$(jq -r '.tool_input.file_path // empty'); if [[ \"$file\" == emoji/* || \"$file\" == */emoji/* ]]; then echo 'BLOCKED: Emoji image files should not be written by Claude. Manage images manually or use /dedup-check.' >&2; exit 2; fi"
+          }
+        ]
+      }
+    ],
+    "PostToolUse": [
+      {
+        "matcher": "Edit|Write",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "file=$(jq -r '.tool_input.file_path // empty'); if [[ \"$file\" == *.py ]]; then uv run ruff check --fix \"$file\" 2>&1 | tail -5 && uv run ruff format \"$file\" 2>&1 | tail -3; fi"
+          }
+        ]
+      },
+      {
+        "matcher": "Edit|Write",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "file=$(jq -r '.tool_input.file_path // empty'); if [[ \"$file\" == *.py ]]; then uv run pytest --tb=short -q 2>&1 | tail -5; fi"
+          }
+        ]
+      }
+    ]
+  }
+}

.claude/skills/dedup-check/SKILL.md

@@ -0,0 +1,10 @@
+---
+name: dedup-check
+description: Run dedup in dry-run mode and report duplicate groups found
+disable-model-invocation: true
+---
+
+## Steps
+
+1. Run `uv run dedup --dry-run` from the project root
+2. Summarize the output — report how many duplicate groups were found and which files are involved

.claude/skills/regen-listings/SKILL.md

@@ -0,0 +1,11 @@
+---
+name: regen-listings
+description: Regenerate README.md and index.html from emoji/ contents and verify output
+disable-model-invocation: true
+---
+
+## Steps
+
+1. Run `uv run python3 create_listing.py` from the project root
+2. Confirm both `README.md` and `index.html` exist and are non-empty
+3. Report the file sizes of both generated files