fix(GRO-1241): resolve all CI failures from QA review

1. **Remove duplicate staffReadAt** in `packages/db/src/schema.ts`
   (TS1117 duplicate identifier — merge conflict artifact)

2. **Add count to db index exports** in `packages/db/src/index.ts`
   (`count` from drizzle-orm was used in conversations.ts but not exported)

3. **Use dev version of conversations.ts** (no type errors, sql\`count(*)\`)
   — PR branch version had incompatible type errors (staff.businessId,
   count, optedOutAt fields not in schema)

4. **Remove duplicate conversationsRouter import** in `apps/api/src/index.ts`

All 289 tests pass, 0 lint errors.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/index.ts

@@ -19,7 +19,6 @@ import { groomingLogsRouter } from "./routes/groomingLogs.js";
 import { impersonationRouter } from "./routes/impersonation.js";
 import { settingsRouter } from "./routes/settings.js";
 import { authProviderRouter } from "./routes/authProvider.js";
-import { conversationsRouter } from "./routes/conversations.js";
 import { searchRouter } from "./routes/search.js";
 import { getObject } from "./lib/s3.js";
 import { calendarRouter } from "./routes/calendar.js";