feat: migrate commands to skills

.claude/skills/session-management/references/checkpoints.md

@@ -0,0 +1,48 @@
+# Checkpoints
+
+## Save Checkpoint
+
+```bash
+/checkpoint save [name]
+```
+
+Creates a git stash with metadata in `.claude/checkpoints/[name].json`:
+
+```json
+{
+  "name": "feature-auth",
+  "created": "2026-04-19T14:30:00Z",
+  "git_stash": "stash@{0}",
+  "files_in_context": ["src/auth/login.ts", "src/auth/token.ts"],
+  "current_task": "Implementing JWT refresh",
+  "notes": "User-provided notes"
+}
+```
+
+## List Checkpoints
+
+```bash
+/checkpoint list
+```
+
+## Restore Checkpoint
+
+```bash
+/checkpoint restore [name]
+```
+
+Applies git stash, loads metadata, summarizes restored context.
+
+## Delete Checkpoint
+
+```bash
+/checkpoint delete [name]
+```
+
+## Auto-Checkpoint Triggers
+
+Suggest checkpoints before:
+- Major refactoring
+- Context switches
+- Risky operations
+- Natural breakpoints in complex work