calendar: use todoman for VTODO list/complete/delete/check

Replaces custom .ics parsing with todoman CLI (--porcelain for JSON).
todo add still uses icalendar directly (needs ICS creation + email).
Updates MIGRATION.md with todoman install/config instructions.

skills/calendar/MIGRATION.md

@@ -8,15 +8,52 @@
 | `reminders/active.md` (markdown table) | `calendars/tasks/*.ics` (RFC 5545 VTODO) |
 | Local only, no sync | CalDAV sync to all devices via vdirsyncer |
 | No native reminders | VALARM triggers on phone/desktop |
-| Cron reads markdown | Cron reads .ics files |
+| Cron reads markdown | Cron reads .ics via todoman |
+| Custom Python parsing | todoman for robust RFC 5545 VTODO handling |
 
 ## Prerequisites
 
-- [ ] `calendar.sh todo add --dry-run` works (tested in current session)
+- [ ] Install todoman (see below)
+- [ ] Configure todoman (see below)
+- [ ] `calendar.sh todo add --dry-run` works
 - [ ] `~/.openclaw/workspace/calendars/tasks/` directory exists (auto-created by `todo add`)
 - [ ] vdirsyncer has a `cal/tasks` pair configured
 - [ ] Live tests 8-12 from `TESTING.md` pass on the Linux machine
 
+## Step 0: Install and configure todoman
+
+### Install
+
+```bash
+# Debian/Ubuntu (the agent's Linux machine)
+pip install todoman
+
+# macOS (Homebrew)
+brew install todoman
+```
+
+The CLI command is `todo`.
+
+### Configure
+
+Create `~/.config/todoman/config.py`:
+
+```python
+path = "~/.openclaw/workspace/calendars/tasks/"
+date_format = "%Y-%m-%d"
+time_format = "%H:%M"
+default_due = 24
+default_priority = 0
+humanize = True
+```
+
+### Verify
+
+```bash
+# Should list todos (or show empty list without errors)
+todo list
+```
+
 ## Step 1: Migrate pending reminders
 
 Two items are pending in `reminders/active.md`:
@@ -37,6 +74,8 @@ $SKILL_DIR/scripts/calendar.sh todo add \
   --description "询问iui报销相关事宜"
 ```
 
+Note: `todo add` emails each item to `mail@luyx.org`. This is expected.
+
 Verify:
 ```bash
 $SKILL_DIR/scripts/calendar.sh todo list
@@ -50,27 +89,29 @@ Ask the agent to set up a daily cron job via `openclaw cron`:
 > `~/.openclaw/workspace/skills/calendar/scripts/calendar.sh todo check`
 > and emails the output to mail@luyx.org with subject "📋 今日待办清单"
 
-The old `reminder_check.py` cron in `crontab.txt` should be removed by the agent at the same time.
+The old `reminder_check.py` cron should be removed by the agent at the same time.
 
 ## Step 3: Verify
 
-- [ ] `todo list` shows both migrated items
+- [ ] `todo list` (todoman directly) shows both migrated items
+- [ ] `calendar.sh todo list` shows both items with Chinese priority labels
 - [ ] `vdirsyncer sync` completes without errors
 - [ ] Todos appear on phone/CalDAV client
 - [ ] Next morning's cron email arrives with the new format
 
-## Step 4: Clean up (optional, after confidence period)
+## Step 4: Clean up
 
 After a few days of successful operation:
 
-- `reminders/active.md` — can be archived or deleted
-- `scripts/reminder_check.py` — can be removed
-- `reminders/` directory — can be removed
-- Old cron entry in `crontab.txt` — should already be gone
+```bash
+# Remove old reminder system
+rm scripts/reminder_check.py
+rm -r reminders/
+```
 
 ## Rollback
 
-If something goes wrong, the old system is still intact:
+If something goes wrong, the old system is still intact until Step 4:
 - `reminders/active.md` is unchanged
 - `scripts/reminder_check.py` still works
 - Re-add the old cron entry to restore the previous behavior