chore(deps): bump the AI SDK to 7.0.85

[guillermoscript]

What

Routine bump of the ai package (7.0.48 → 7.0.85) and the four @ai-sdk/* providers we use, plus the transitive @ai-sdk/gateway / provider / provider-utils packages they pull in.

Closes #

Why

The manifest floors had drifted well behind what was actually installed locally. This pins them to the versions that are now in the lockfile, so a fresh clone installs what we tested rather than something older.

The lockfile diff is contained to the ai-sdk family — nothing else moves. In particular the exact stripe pin from #638 and its apiVersion literal are untouched.

How to QA

No behaviour change is expected; this is a dependency-only PR. To confirm the AI surfaces still work end to end:

1. npm ci && npm run db:reset, then npm run dev.
2. Sign in as student@e2etest.com / password123 on default.lvh.me:3000.
3. Open any lesson and use the AI chat — send a message with and without an image attachment (the flow from feat(ai): let students attach images in every AI chat #633). Streaming should be unchanged.
4. Open an exercise and submit it for AI evaluation; confirm feedback still streams back.

Screenshots / GIF

n/a — no user-visible change.

Checklist

• npm run typecheck and npm run test:unit pass (1000/1000)
• npm run build passes
• Every new tenant-scoped query filters by tenant_id (or the table genuinely has no such column) — no queries touched
• Tested with every relevant role (student / teacher / admin) — n/a, no behaviour change
• Loading and error states handled — n/a
• New UI strings added to both messages/en.json and messages/es.json — none added
• Migration (if any) applies cleanly on npm run db:reset — no migration

🤖 Generated with Claude Code

https://claude.ai/code/session_01CZmStQ3YnZMQkr2sp2FeGr