feat: complete assigned profile, inventory, and event fields

[hameedx01]

Summary

• add authenticated profile-name updates with trimmed, length-limited validation
• add an atomic ticket inventory update that permits quantityTotal === quantityIssued and returns 409 below that boundary
• add event descriptions, nullable image URLs, and Intl-validated IANA timezones, including a safe migration for existing events
• document the new fields and endpoints and update seed/test fixtures

Closes #59
Closes #101
Closes #103
Closes #105

Testing

• 158 focused Jest tests pass across users, events, DTOs, controllers, and services
• ESLint passes for changed application and unit-test files
• npx prisma validate passes
• git diff --check passes
• npx tsc --noEmit — upstream already fails on request middleware mocks, reconciliation test inference, Stellar SDK types, duplicate test properties, and Prisma JSON typing
• npm test — upstream reproduces the same 35 failures in Stellar/ticket suites; 1101 tests pass
• npm run audit:check — upstream dependencies currently report high advisories in @stellar/stellar-sdk/axios and a critical proxy-addr advisory
• npm run docs:check — upstream .env.example is missing the already-validated SOROBAN_RPC_TIMEOUT_MS

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