Add typed agent-server compatibility helpers

[neubig]

Summary

• add an agent-server compatibility helper with AgentServerVersionError
• define the workspace minimum server version as 1.23.0
• add and export WorkspacesClient so workspace endpoints fail with a typed version error before hitting missing routes on old servers
• allow RemoteEventsList construction from client options and add ConversationClient.switchLLM so canvas callers do not need to instantiate HttpClient directly

Verification

• npm run build
• npm run format:check
• npm run lint (existing warnings only)
• npm test -- --runTestsByPath src/__tests__/api-clients.test.ts
• npm test

[all-hands-bot]

🟢 Good taste - Clean implementation with proper abstractions.

This PR adds type-safe agent-server version compatibility checking with intelligent caching. The semantic version parsing is solid, error handling is clear, and the WorkspacesClient integration is elegant. All changes are browser-compatible and backward compatible.

[RISK ASSESSMENT]

• [Overall PR] ⚠️ Risk Assessment: 🟢 LOW

This is a well-contained feature addition with comprehensive test coverage. The version checking logic prevents runtime errors by failing fast with clear error messages. No breaking changes, no dependencies added, and the caching strategy using WeakMap ensures proper garbage collection.

VERDICT:
✅ Worth merging - Solid implementation, no issues found.

KEY INSIGHT:
The cached version check prevents redundant server_info calls while still allowing per-HttpClient-instance version verification, striking a good balance between performance and correctness.

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[all-hands-bot]

🟢 Good taste - Clean implementation with proper abstractions and elegant version checking.

The semantic version parsing is solid, caching strategy is smart (WeakMap), and the error handling provides clear feedback. All changes are browser-compatible and backward compatible. Just one minor type safety improvement suggested.

[IMPROVEMENT OPPORTUNITIES]

• [src/client/conversation-client.ts, Line 141] Type Safety: Use the existing LLM interface instead of unknown for better type safety and IDE support.

[RISK ASSESSMENT]

• [Overall PR] ⚠️ Risk Assessment: 🟢 LOW

This is a well-contained additive feature with comprehensive test coverage. Version checking logic is correct, all changes are backward compatible, and the caching mechanism is elegant. No breaking changes or security concerns.

VERDICT:
✅ Worth merging: Clean architecture with one minor type improvement suggested

KEY INSIGHT:
The WeakMap-based caching elegantly solves the "check once, trust always" problem while automatically cleaning up when client instances are garbage collected.

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Workflow run: https://github.com/OpenHands/typescript-client/actions/runs/26331261532