fix: replace as-unknown-as casts with safer patterns (#9107)

## Summary

- Replace 83 `as unknown as` double casts with safer alternatives across
33 files
- Use `as Partial<X> as X` pattern where TypeScript allows it
- Create/reuse factory functions from `litegraphTestUtils.ts` for mock
objects
- Widen `getWorkflowDataFromFile` return type to include `ComfyMetadata`
directly
- Reduce total `as unknown as` count from ~153 to 71

The remaining 71 occurrences are genuinely necessary due to cross-schema
casts, generic variance, missing index signatures, Float64Array-to-tuple
conversions, and DOM type incompatibilities.

## Test plan

- [x] `pnpm typecheck` passes
- [x] `pnpm lint` passes
- [x] All affected unit tests pass

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9107-fix-replace-as-unknown-as-casts-with-safer-patterns-3106d73d3650815cb5bcd613ad635bd7)
by [Unito](https://www.unito.io)

src/platform/telemetry/utils/__tests__/checkoutAttribution.test.ts

@@ -38,7 +38,7 @@ describe('getCheckoutAttribution', () => {
         callback(valueByField[fieldName])
       }
     )
-    window.gtag = gtagSpy as unknown as Window['gtag']
+    window.gtag = gtagSpy as Partial<Window['gtag']> as Window['gtag']
 
     window.history.pushState(
       {},
@@ -108,7 +108,7 @@ describe('getCheckoutAttribution', () => {
         callback(valueByField[fieldName])
       }
     )
-    window.gtag = gtagSpy as unknown as Window['gtag']
+    window.gtag = gtagSpy as Partial<Window['gtag']> as Window['gtag']
 
     const attribution = await getCheckoutAttribution()
 

src/platform/workflow/core/services/workflowService.test.ts

@@ -91,7 +91,7 @@ function createWorkflow(
       activeState: { nodes: [], links: [] },
       changeTracker: { reset: vi.fn(), restore: vi.fn() }
     })
-  } as unknown as ComfyWorkflow
+  } as Partial<ComfyWorkflow> as ComfyWorkflow
 }
 
 function enableWarningSettings() {
@@ -181,7 +181,10 @@ describe('useWorkflowService', () => {
       vi.mocked(app.loadGraphData).mockImplementation(
         async (_data, _clean, _restore, wf) => {
           ;(
-            workflowStore as unknown as Record<string, unknown>
+            workflowStore as Partial<Record<string, unknown>> as Record<
+              string,
+              unknown
+            >
           ).activeWorkflow = wf
         }
       )