fix(types): bring real code to zero TypeScript errors, fix three latent bugs

Continues the cleanup from 164 errors down to 88, all of which now sit in
MemStorage — the in-memory dev mock — documented as known debt. Production
server code and the entire client are at zero errors.

Three genuine defects surfaced by the types and fixed:
- deleteAnnouncement returned void while routes check the result and answer
  404 "not found" on falsy: deleting an announcement succeeded in DB but the
  API reported failure on the fallback paths; it now returns a real boolean
- AnnouncementMemoryStorage declared getAnnouncement twice; the first
  implementation was dead at runtime (second definition wins) and is removed
- one route called storage.getDeliveryById(), a method that does not exist,
  crashing with a TypeError whenever hit; it now calls getDelivery()

Everything else is type-level only (annotations, null-to-undefined for
inline styles, honest signatures for markClientCalled's comment parameter
and the invoice verification result's invoiceAmountTTC field), verified
behavior-neutral: client build, production server bundle and the SMTP
end-to-end test all pass unchanged.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FHdE9nEh8zHhQNGpCgrtYe

server/db.production.ts

@@ -46,9 +46,9 @@ pool.on('error', (err) => {
   } catch (error) {
     console.error('❌ DB: Database migrations failed with error:', error);
     console.error('❌ DB: Migration failure details:', {
-      name: error?.name,
-      message: error?.message,
-      code: error?.code
+      name: (error as any)?.name,
+      message: (error as any)?.message,
+      code: (error as any)?.code
     });
     // Don't fail the application startup for migration errors
   }