Manual save button, file requirement labels, fix config revert bug

- Replace auto-save with manual floating save bar that appears when config
  has unsaved changes (Discard / Save Changes buttons). Fixes race condition
  where server sync overwrote local state after toggling switches.
- Show file requirement name (e.g. "Pitch Deck", "Presentation") above each
  document in the All Uploaded Files section on project detail page
- Pass requirement relation data through to FileViewer component

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/(admin)/admin/projects/[id]/page.tsx

@@ -677,6 +677,13 @@ function ProjectDetailContent({ projectId }: { projectId: string }) {
                     detectedLang: f.detectedLang,
                     langConfidence: f.langConfidence,
                     analyzedAt: f.analyzedAt ? String(f.analyzedAt) : null,
+                    requirementId: f.requirementId,
+                    requirement: f.requirement ? {
+                      id: f.requirement.id,
+                      name: f.requirement.name,
+                      description: f.requirement.description,
+                      isRequired: f.requirement.isRequired,
+                    } : null,
                   }))}
                 />
               </div>