feat(server): expose session resume

[firatoezcan]

Sorry, agent went rogue. I mean session.resume would be cool to have, but I am just forking opencode thanks for the work though!!

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[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Based on my search, the most relevant related PR is:

PR #46139: fix(session): resume loop when user message arrives during question prompt
#46139

This PR is related because it also deals with session resume behavior and question prompts, which directly intersects with the session resume operation being exposed in PR #46197.

The PR description also mentions "Related to #35443", which suggests there may be additional context in that issue, though it's not another PR.

All other search results either address different session-related features (like scoped handles, subagent interruption, etc.) or are unrelated to the session resume functionality.