chore: Fix all lint errors and remove unused code

- Fix 75 ESLint errors by updating eslint.config.mjs:
  - Add missing browser globals (MouseEvent, AbortController, Response, etc.)
  - Add Vite define global (__APP_VERSION__)
  - Configure @ts-nocheck to require descriptions
  - Add no-unused-vars rule for .mjs scripts

- Fix runtime bug in agent-output-modal.tsx (setOutput -> setStreamedContent)

- Remove ~120 unused variable warnings across 97 files:
  - Remove unused imports (React hooks, lucide icons, types)
  - Remove unused constants and variables
  - Remove unused function definitions
  - Prefix intentionally unused parameters with underscore

- Add descriptions to all @ts-nocheck comments (25 files)

- Clean up misc issues:
  - Remove invalid deprecation plugin comments
  - Fix eslint-disable comment placement
  - Add missing RefreshCw import in code-view.tsx

Reduces lint warnings from ~300 to 67 (all remaining are no-explicit-any)

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

apps/ui/src/components/views/spec-view/components/edit-mode/features-section.tsx

@@ -32,6 +32,7 @@ function featureToInternal(feature: Feature): FeatureWithId {
 }
 
 function internalToFeature(internal: FeatureWithId): Feature {
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
   const { _id, _locationIds, ...feature } = internal;
   return feature;
 }

apps/ui/src/components/views/spec-view/components/edit-mode/roadmap-section.tsx

@@ -27,6 +27,7 @@ function phaseToInternal(phase: RoadmapPhase): PhaseWithId {
 }
 
 function internalToPhase(internal: PhaseWithId): RoadmapPhase {
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
   const { _id, ...phase } = internal;
   return phase;
 }