feat: add ClaudeKit configuration

Add agent definitions, slash commands, hooks, and settings for
Claude Code project tooling.

.claude/commands/checkpoint/list.md

@@ -0,0 +1,34 @@
+---
+description: List all Claude Code checkpoints with time and description
+category: workflow
+allowed-tools: Bash(git stash:*)
+---
+
+## List Claude Code checkpoints
+
+Display all checkpoints created by Claude Code during this and previous sessions.
+
+## Task
+
+List all Claude Code checkpoints. Steps:
+
+1. Run `git stash list` to get all stashes
+2. Filter for lines containing "claude-checkpoint:" using grep or by parsing the output
+3. For each matching stash line (format: `stash@{n}: On branch: message`):
+   - Extract the stash number from `stash@{n}`
+   - Extract the branch name after "On "
+   - Extract the checkpoint description after "claude-checkpoint: "
+   - Use `git log -1 --format="%ai" stash@{n}` to get the timestamp for each stash
+
+4. Format and display as:
+   ```
+   Claude Code Checkpoints:
+   [n] YYYY-MM-DD HH:MM:SS - Description (branch)
+   ```
+   Where n is the stash index number
+
+5. If `git stash list | grep "claude-checkpoint:"` returns nothing, display:
+   "No checkpoints found. Use /checkpoint [description] to create one."
+
+Example: A stash line like `stash@{2}: On main: claude-checkpoint: before auth refactor`
+Should display as: `[2] 2025-01-15 10:30:45 - before auth refactor (main)`