feat: add post-migration cleanup for OpenClaw directories (#4100)

After migrating from OpenClaw, leftover workspace directories contain
state files (todo.json, sessions, logs) that confuse the agent — it
discovers them and reads/writes to stale locations instead of the
Hermes state directory, causing issues like cron jobs reading a
different todo list than interactive sessions.

Changes:
- hermes claw migrate now offers to archive the source directory after
  successful migration (rename to .pre-migration, not delete)
- New `hermes claw cleanup` subcommand for users who already migrated
  and need to archive leftover OpenClaw directories
- Migration notes updated with explicit cleanup guidance
- 42 tests covering all new functionality

Reported by SteveSkedasticity — multiple todo.json files across
~/.hermes/, ~/.openclaw/workspace/, and ~/.openclaw/workspace-assistant/
caused cron jobs to read from wrong locations.

optional-skills/migration/openclaw-migration/scripts/openclaw_to_hermes.py

@@ -2455,9 +2455,24 @@ class Migrator:
             notes.append("")
 
         notes.extend([
+            "## IMPORTANT: Archive the OpenClaw Directory",
+            "",
+            "After migration, your OpenClaw directory still exists on disk with workspace",
+            "state files (todo.json, sessions, logs). If the Hermes agent discovers these",
+            "directories, it may read/write to them instead of the Hermes state, causing",
+            "confusion (e.g., cron jobs reading a different todo list than interactive sessions).",
+            "",
+            "**Strongly recommended:** Run `hermes claw cleanup` to rename the OpenClaw",
+            "directory to `.openclaw.pre-migration`. This prevents the agent from finding it.",
+            "The directory is renamed, not deleted — you can undo this at any time.",
+            "",
+            "If you skip this step and notice the agent getting confused about workspaces",
+            "or todo lists, run `hermes claw cleanup` to fix it.",
+            "",
             "## Hermes-Specific Setup",
             "",
             "After migration, you may want to:",
+            "- Run `hermes claw cleanup` to archive the OpenClaw directory (prevents state confusion)",
             "- Run `hermes setup` to configure any remaining settings",
             "- Run `hermes mcp list` to verify MCP servers were imported correctly",
             "- Run `hermes cron` to recreate scheduled tasks (see archive/cron-config.json)",