fix(test): update TerminalView write assertions and harden opencode serve port

[danshapiro]

Summary

Two test-only fixes that bring the suite back to green.

1. TerminalView stale write() assertions (3 assertions)

The backpressure fix (dd12912b) made TerminalView always pass a completeRenderedFrame callback as the second argument to term.write(). That commit updated lifecycle.test.tsx but missed TerminalView.osc52.test.tsx (×2) and TerminalView.renderer.test.tsx (×1), which still asserted write() was called with undefined. Switched them to the established write.mock.calls.some((call) => call[0] === '…') idiom that verifies the written data without pinning the now-present callback argument.

2. OpenCode real-provider contract test hardcoded serve port

coding-cli-session-contract.test.ts hardcoded serve port 46123. A leaked orphan opencode serve holding that port let the --attach run silently connect to the stranger (different XDG_DATA_HOME → wrong DB), so the session never landed in the watched DB and the test timed out.

Fix: allocate a free ephemeral port via allocateLocalhostPort() and fail fast on serve startup errors, through a new startOpencodeServe harness helper that mirrors the existing startCodexAppServer pattern.

Test plan

• Full coordinated suite green (npm test): full-suite success exit=0.
• npm run typecheck (client + server): clean.
• OpenCode contract test passes (~23s); full real-contract file: 7 passed / 2 skipped (binary-gated).

🤖 Generated with Claude Code

[glowforgedan]

Test-only fixes verified green (full coordinated suite + typecheck). Stale write() assertions updated to match the backpressure callback change; opencode contract test moved off the hardcoded port to a free ephemeral port with fast-fail. LGTM.