fix(dashboard): populate cron delivery dropdown from configured platforms (#40218)

* fix: respect disabled auto-compaction on context overflow

Port from anomalyco/opencode#30749.

When compression.enabled is false, NO automatic compaction trigger may
fire. The proactive token-threshold paths (preflight + post-response
should_compress gate) already honoured the setting, but the three
provider-overflow recovery paths in the agent loop — long-context-tier
429, 413 payload-too-large, and context-overflow — called
_compress_context() unconditionally, silently compressing and rotating
the session against the user's explicit choice.

Add a single guard at the top of the overflow-recovery dispatch: when
compression is disabled and the error is one of those three overflow
classes, surface a terminal error (compaction_disabled: True) telling the
user to /compress manually, /new, switch to a larger-context model, or
reduce attachments. Manual /compress (force=True) is unaffected — it never
enters this loop.

Tests: new TestOverflowWithCompactionDisabled (413 + 400 overflow don't
compress when disabled; control case still compresses when enabled).
Existing overflow-recovery tests updated to enable compaction explicitly
(they verify the recovery fires); fixture defaults flipped to True to
match production (compression.enabled defaults to True).

* fix(dashboard): populate cron delivery dropdown from configured platforms

The dashboard cron-create/edit dropdown hardcoded five delivery options
(local, telegram, discord, slack, email), so users on Matrix — or any
other backend-supported platform — had no way to pick their channel even
though the cron scheduler delivers to all of them. It also offered
Telegram/Discord/etc. to users who never set those up.

- cron/scheduler.py: add cron_delivery_targets() — the single source of
  truth. Intersects gateway-configured platforms with cron-deliverable
  ones and reports whether each platform's home channel is set.
- web_server.py: GET /api/cron/delivery-targets exposes that list (+ the
  implicit local option) to the dashboard.
- CronPage.tsx: both modals render options from the endpoint. Configured
  platforms missing a home channel still appear, annotated "set a home
  channel first" (option B), so the user knows what to fix. Edit modal
  preserves a job's current target even if it's no longer configured.
  Local-only state shows a "configure a platform under Channels" hint.

Validation: scheduler + endpoint E2E'd with a Matrix gateway (home set
and unset); 5 new tests; tests/cron + tests/hermes_cli/test_web_server
green (366 passed).

hermes_cli/web_server.py

@@ -5554,6 +5554,34 @@ async def create_cron_job(body: CronJobCreate, profile: str = "default"):
         raise HTTPException(status_code=400, detail=str(e))
 
 
+@app.get("/api/cron/delivery-targets")
+async def get_cron_delivery_targets():
+    """Delivery targets the cron dropdown should offer.
+
+    Always includes the implicit ``local`` option. Beyond that, the list is
+    derived dynamically from the configured gateway platforms via
+    ``cron.scheduler.cron_delivery_targets()`` — no hardcoded platform list. A
+    configured platform that hasn't set its cron home channel is still returned
+    with ``home_target_set: false`` so the UI can surface it as "configure a
+    home channel first" rather than hiding it.
+    """
+    targets = [
+        {
+            "id": "local",
+            "name": "Local (save only)",
+            "home_target_set": True,
+            "home_env_var": None,
+        }
+    ]
+    try:
+        from cron.scheduler import cron_delivery_targets
+
+        targets.extend(cron_delivery_targets())
+    except Exception:
+        _log.exception("GET /api/cron/delivery-targets failed")
+    return {"targets": targets}
+
+
 @app.put("/api/cron/jobs/{job_id}")
 async def update_cron_job(job_id: str, body: CronJobUpdate, profile: Optional[str] = None):
     selected = profile or _find_cron_job_profile(job_id)