feat(database): add opt-in live document updates in the data explorer

[JohnChantz]

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• It's submitted to the master branch
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx, where "xxx" is the issue number)

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Other information:

Summary

• Adds opt-in live document updates in the data explorer: subscribe to MongoDB change streams through a short-lived admin socket ticket and show pending updates without auto-refreshing the grid.
• Schema settings include copyable JS, Postman, and Admin connection snippets so developers can subscribe without guessing the handshake.
• Normalizes the schema indexes API when the Database module returns a raw array instead of { indexes } (model settings tab).
• Split from feat(router): add event relays administration page #321 (database live updates only; Event Relays is feat(router): add event relays administration page #327).

Test plan

• Enable realtime on Database settings and on a schema, then open that schema in the data explorer
• Toggle live updates, mutate a document elsewhere, and confirm a pending-update count without the grid auto-refreshing
• Apply updates and confirm the table refreshes
• Copy JS / Postman / Admin snippets from schema settings
• Open schema indexes on the model settings tab (raw array response should not throw)
• pnpm test:realtime
• node --experimental-strip-types --test src/lib/database/schema-indexes.test.ts