refactor(runtime): remove the opencode adapter and in-sandbox serve #66

Parent

#62

What to build

Remove the opencode-specific runtime (ADR 0013 §1, §4, §6).

• Delete:
  • runtime/opencode-adapter.ts, extractOpencodeSignal;
  • lib/sandbox-config.ts and the opencode.json write;
  • AgentAdapter.prepareWorkspace and StartRunOptions.prepareWorkspace;
  • the @tanstack/ai-opencode, @tanstack/ai-sandbox and -local-process dependencies;
  • the .tanstack-projected-* and data/ ignores, if nothing else needs them.
• Re-record the replay corpus with the ACP adapter, for both agents. The replay adapter
  takes signals from the recorded stream without opencode event names. Keep the old corpora only
  where a test needs historical opencode chunks, such as the SPA folding old logs.
• Simplify agent-step.ts: rewrite the abort-chain commentary. Keep abortableIterable and
  AGENT_TEARDOWN_GRACE_MS only if the tests still need them.

Acceptance

• bun run check and bun run test:e2e green.
• No opencode serve or free-port code remains.