feat: proactive notifications — web_push channel + daily reminder check

Routes web_push through notification.py alongside NCT/email/Google Chat,
and fires daily reminder summaries via the scheduler.

- notification.py: _notify_web_push() + "web_push" case in notify();
  all four channels (web_push/email/nextcloud/google_chat) now routable
- scheduler.py: _run_reminder_check() daily at 09:00 — reads due reminders
  per persona via set_context(), formats up to 3 entries, calls notify()
- routers/settings.py: "web_push" added to valid notification_channel values
- static/settings.html: "Browser Push Notification" option in channel selector
- TODO__Agents.md: proactive notifications section marked complete

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/scheduler.py

@@ -69,6 +69,47 @@ async def _run_long() -> None:
             logger.error("auto distill long [%s/%s] failed: %s", u, p, e)
 
 
+async def _run_reminder_check() -> None:
+    """Notify users of any due or overdue reminders (fires once daily at 09:00)."""
+    import re
+    from notification import notify
+    from persona import set_context
+
+    for u, p in _all_personas():
+        try:
+            set_context(u, p)
+            from tools.reminders import load_due_reminders
+            content = load_due_reminders()
+            if not content:
+                continue
+
+            # Extract numbered entries (lines like "1. [label] text" or "1. text")
+            entries = []
+            for line in content.splitlines():
+                m = re.match(r"^\d+\.\s+(.+)", line.strip())
+                if m:
+                    # Strip status tags ([OVERDUE], [due TODAY], etc.) for display
+                    text = re.sub(r"\[(OVERDUE|due TODAY|due: \S+)\]", "", m.group(1)).strip()
+                    if text:
+                        entries.append(text)
+
+            if not entries:
+                continue
+
+            count = len(entries)
+            if count == 1:
+                msg = f"Reminder: {entries[0]}"
+            else:
+                bullet_list = "\n".join(f"• {e}" for e in entries[:3])
+                tail = f"\n…and {count - 3} more" if count > 3 else ""
+                msg = f"{count} reminders due:\n{bullet_list}{tail}"
+
+            await notify(u, msg)
+            logger.info("reminder check [%s/%s]: notified %d reminder(s)", u, p, count)
+        except Exception as e:
+            logger.error("reminder check [%s/%s] failed: %s", u, p, e)
+
+
 def get_scheduler() -> AsyncIOScheduler | None:
     """Return the running scheduler instance (used by cron tools for live add/remove)."""
     return _scheduler
@@ -93,6 +134,10 @@ def start() -> None:
         _scheduler.add_job(_run_long, "cron", day=1, hour=4, minute=0, id="distill_long")
         logger.info("scheduled: distill_long monthly on 1st at 04:00")
 
+    # Daily reminder notification check — 09:00
+    _scheduler.add_job(_run_reminder_check, "cron", hour=9, minute=0, id="reminder_check")
+    logger.info("scheduled: reminder_check daily at 09:00")
+
     # Load user-defined cron jobs from CRONS.json
     _load_user_crons()