feat(desktop): split cron sessions into their own sidebar section

Scheduler sessions (source=cron) were listed in recents, where their
`[IMPORTANT: …]` first-message previews spammed the list — and because
cron runs are always newest, a burst of them consumed the whole recents
page budget and starved real conversations (sidebar showed 0 sessions).

Recents and cron jobs are now two independent lists:
- Backend: /api/sessions + /api/profiles/sessions accept source /
  exclude_sources; session_count gains exclude_sources. Recents query
  excludes cron; the cron section queries source=cron.
- Desktop: separate $cronSessions store + refreshCronSessions fetch, a
  collapsed (persisted) "Cron jobs" section below Sessions that only
  renders when cron sessions exist, with its own bounded scroller.

hermes_cli/web_server.py

@@ -1574,6 +1574,8 @@ async def get_sessions(
     min_messages: int = 0,
     archived: str = "exclude",
     order: str = "created",
+    source: str = None,
+    exclude_sources: str = None,
 ):
     """List sessions.
 
@@ -1604,7 +1606,14 @@ async def get_sessions(
             min_message_count = max(0, min_messages)
             archived_only = archived == "only"
             include_archived = archived == "include"
+            # Optional source scoping: ``source`` includes a single class,
+            # ``exclude_sources`` (comma-separated) drops classes. The desktop
+            # uses these to split recents (exclude=cron) from the cron-jobs
+            # section (source=cron) into two independent lists.
+            exclude_list = [s for s in (exclude_sources or "").split(",") if s.strip()]
             sessions = db.list_sessions_rich(
+                source=source or None,
+                exclude_sources=exclude_list or None,
                 limit=limit,
                 offset=offset,
                 min_message_count=min_message_count,
@@ -1613,6 +1622,8 @@ async def get_sessions(
                 order_by_last_active=order == "recent",
             )
             total = db.session_count(
+                source=source or None,
+                exclude_sources=exclude_list or None,
                 min_message_count=min_message_count,
                 include_archived=include_archived,
                 archived_only=archived_only,
@@ -1642,6 +1653,8 @@ async def get_profiles_sessions(
     archived: str = "exclude",
     order: str = "recent",
     profile: str = "all",
+    source: str = None,
+    exclude_sources: str = None,
 ):
     """Unified, read-only session list aggregated across ALL profiles.
 
@@ -1677,6 +1690,11 @@ async def get_profiles_sessions(
     min_message_count = max(0, min_messages)
     archived_only = archived == "only"
     include_archived = archived == "include"
+    # Source scoping (see /api/sessions): recents pass exclude_sources=cron,
+    # the cron-jobs section passes source=cron — two independent lists so
+    # newest cron sessions can't starve the recents page.
+    source_filter = source or None
+    exclude_list = [s for s in (exclude_sources or "").split(",") if s.strip()]
     # Over-fetch per profile so the merged+sorted window is correct for the
     # requested page. Capped so a huge profile can't blow up the response.
     per_profile = min(max(limit + offset, limit), 500)
@@ -1700,6 +1718,8 @@ async def get_profiles_sessions(
             continue
         try:
             rows = db.list_sessions_rich(
+                source=source_filter,
+                exclude_sources=exclude_list or None,
                 limit=per_profile,
                 offset=0,
                 min_message_count=min_message_count,
@@ -1708,6 +1728,8 @@ async def get_profiles_sessions(
                 order_by_last_active=order == "recent",
             )
             profile_total = db.session_count(
+                source=source_filter,
+                exclude_sources=exclude_list or None,
                 min_message_count=min_message_count,
                 include_archived=include_archived,
                 archived_only=archived_only,