fix: address second code review findings for rollover storage

- C3: Make retain_policy global-only by hiding from per-camera settings
  UI and removing from CameraConfig TypeScript type
- C4: Add missing units field to StorageBreakdown TypeScript type to
  match API response
- I3: Add 24-hour grace period for deleted camera recordings in rollover
  mode to prevent data loss if camera is temporarily removed from config
- I6: Deduplicate model_validator warning by using module-level flag to
  prevent N+1 duplicate warnings during config propagation
- S5: Add debug log when skipping time-based expiry in rollover mode and
  clean up redundant if/not-if to if/else

web/src/components/config-form/section-configs/record.ts

@@ -44,6 +44,7 @@ const record: SectionConfigOverrides = {
   },
   camera: {
     restartRequired: [],
+    hiddenFields: ["retain_policy"],
   },
 };
 

web/src/types/frigateConfig.ts

@@ -191,7 +191,6 @@ export interface CameraConfig {
   record: {
     enabled: boolean;
     enabled_in_config: boolean;
-    retain_policy: "time" | "continuous_rollover";
     alerts: {
       post_capture: number;
       pre_capture: number;
@@ -625,4 +624,5 @@ export type StorageBreakdown = {
   overwritable: number;
   event_retention: number;
   protected: number;
+  units: string;
 };