v0.27.0:0 - in-app settings gear + swap-lock route fix

Move the ~20 optional cluster knobs out of the StartOS "Configure Sparks"
action (now just the 4 required fields) and into a dashboard ⚙ Settings gear,
backed by a /data/app_settings.json overlay keyed by env-var names. One shared
mutable Settings instance + Settings.reload() applies edits live without a
restart; existing installs' values migrate automatically on first boot.

Also: support-service ports (parakeet/kokoro/embed/qdrant + vllm) are now
configurable, and GET /api/swap/lock no longer 404s (it was shadowed by the
/api/swap/{job_id} catch-all). WebhookNotifier is re-pointed on save so its
url/secret reload live too.

image/app/static/style.css

@@ -964,3 +964,13 @@ main {
 .tab-content.active { display: block; }
 
 /* (WhisperX install banner styles removed in v0.13.0:0 — see release notes) */
+
+/* ===== Settings ('gear') dialog ===== */
+.modal#settings-dialog { max-width: 560px; }
+/* Cap the (tall) form so the Save/Cancel actions stay reachable; the grouped
+   fields scroll within. */
+#settings-body { max-height: 60vh; overflow-y: auto; padding-right: 6px; display: flex; flex-direction: column; gap: 12px; }
+.settings-field { display: flex; flex-direction: column; gap: 2px; }
+.settings-help { display: block; line-height: 1.35; }
+.settings-clear { display: inline-flex; align-items: center; gap: 6px; margin-top: 2px; cursor: pointer; }
+.settings-clear input { width: auto; }