fix: make source_ms optional for backward compatibility with existing jobs

Existing jobs in the database don't have source_ms field. Making it
optional allows the API to load these jobs without validation errors.
The re-render task already handles the fallback to original_ms when
source_ms is None.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/models/job.py

@@ -69,7 +69,7 @@ class PausePointData(BaseModel):
     """Pause point timing data for accessible video editing during QC."""
     cue_index: int  # AD cue index this pause point belongs to
     original_ms: float  # Rendered timeline position (ms) - for UI display
-    source_ms: float  # Source video cut point (ms) - for re-rendering
+    source_ms: Optional[float] = None  # Source video cut point (ms) - for re-rendering (None = use original_ms)
     adjusted_ms: Optional[float] = None  # User-adjusted timestamp (ms), None = use original
     min_bound_ms: float  # Minimum allowed value (end of previous AD segment)
     max_bound_ms: float  # Maximum allowed value (start of next AD segment)

backend/app/schemas/accessible_video.py

@@ -131,7 +131,7 @@ class PausePointResponse(BaseModel):
     """Pause point timing data for QC editing."""
     cue_index: int = Field(..., description="AD cue index this pause point belongs to")
     original_ms: float = Field(..., description="Rendered timeline position (ms) - for display")
-    source_ms: float = Field(..., description="Source video cut point (ms) - for re-rendering")
+    source_ms: Optional[float] = Field(None, description="Source video cut point (ms) - for re-rendering (None = use original_ms)")
     adjusted_ms: Optional[float] = Field(None, description="User-adjusted timestamp (ms)")
     min_bound_ms: float = Field(..., description="Minimum allowed value (ms)")
     max_bound_ms: float = Field(..., description="Maximum allowed value (ms)")

frontend/src/types/api.ts

@@ -337,7 +337,7 @@ export interface ReviewNotesListResponse {
 export interface PausePointData {
   cue_index: number;
   original_ms: number;  // Rendered timeline position (for display)
-  source_ms: number;    // Source video cut point (for re-rendering)
+  source_ms: number | null;  // Source video cut point (for re-rendering), null = use original_ms
   adjusted_ms: number | null;
   min_bound_ms: number;
   max_bound_ms: number;