refactor: use the SDK's error predicates instead of local copies

[lmjabreu]

Overview

@doist/comms-sdk 3.3.0 now exports isNotFound, isConflict, isMalformedId, getCommsErrorCode and getCommsErrorString, which #66 had to write locally. This deletes our copies and imports the SDK's.

Reference

Follows @scottlovegrove's review on #66 and Doist/comms-sdk-typescript#83. The 401 and 403 helpers stay here: isForbidden means "a 403 that is not a scope failure", which is our policy rather than a property of the response.

The SDK helpers check instanceof CommsRequestError, as status.ts already does, where ours accepted any object with an httpStatusCode. Nothing in the CLI passes one that isn't an instance.

The bump from 3.0.0 also picks up 3.1.0 and 3.2.0 (thread image reads, retry back-off, a clearer message when a request fails at the network layer), and moves undici to 7.30.0 with it.

Changelog

Internal only. Error messages for 404, malformed ids and other 409s are unchanged.

Test plan

1. tdc thread view id:nope
   • Error: INVALID_REF with the server's message, no stack trace
2. tdc thread view id:<a well-formed id that does not exist>
   • Error: NOT_FOUND
3. tdc thread view id:<a thread you can see>
   • Shows the thread

🤖 Generated with Claude Code

[lmjabreu]

@doistbot /review

[doistbot]

This PR swaps the locally duplicated SDK error predicates (isNotFound, isConflict, isMalformedId, getCommsErrorCode, getCommsErrorString) for the new exports in @doist/comms-sdk 3.3.0, intentionally keeping the 401/403 helpers local since isForbidden encodes CLI policy rather than response shape.

Few things worth tightening:

• The partial SDK mock in src/commands/migrate/migrate.test.ts only provides fetchNewCommsUrls, so it no longer covers the getCommsErrorString import that errors.ts pulls in transitively — update it to spread importActual (as api.test.ts now does) or supply the missing export.

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