feat: add 'hermes claw migrate' command + migration docs

- Add hermes_cli/claw.py with full CLI migration handler:
  - hermes claw migrate (interactive migration with confirmation)
  - --dry-run, --preset, --overwrite, --skill-conflict flags
  - --source for custom OpenClaw path
  - --yes to skip confirmation
  - Clean formatted output matching setup wizard style

- Fix Python 3.11+ @dataclass compatibility bug in dynamic module loading:
  - Register module in sys.modules before exec_module()
  - Fixes both setup.py (PR #981) and new claw.py

- Add 16 tests in tests/hermes_cli/test_claw.py covering:
  - Script discovery (project root, installed, missing)
  - Command routing
  - Dry-run, execute, cancellation, error handling
  - Preset/secrets behavior, report formatting

- Documentation updates:
  - README.md: Add 'hermes claw migrate' to Getting Started, new Migration section
  - docs/migration/openclaw.md: Full migration guide with all options
  - SKILL.md: Add CLI Command section at top of openclaw-migration skill

optional-skills/migration/openclaw-migration/SKILL.md

@@ -14,6 +14,22 @@ metadata:
 
 Use this skill when a user wants to move their OpenClaw setup into Hermes Agent with minimal manual cleanup.
 
+## CLI Command
+
+For a quick, non-interactive migration, use the built-in CLI command:
+
+```bash
+hermes claw migrate              # Full interactive migration
+hermes claw migrate --dry-run    # Preview what would be migrated
+hermes claw migrate --preset user-data   # Migrate without secrets
+hermes claw migrate --overwrite  # Overwrite existing conflicts
+hermes claw migrate --source /custom/path/.openclaw  # Custom source
+```
+
+The CLI command runs the same migration script described below. Use this skill (via the agent) when you want an interactive, guided migration with dry-run previews and per-item conflict resolution.
+
+**First-time setup:** The `hermes setup` wizard automatically detects `~/.openclaw` and offers migration before configuration begins.
+
 ## What this skill does
 
 It uses `scripts/openclaw_to_hermes.py` to: