test: add Terminal Control PR guards

[oribarilan]

Summary

Add separate Terminal Control integration and real-host E2E guards to PR CI, without changing vimcode runtime behavior or the existing fast suite.

• just test retains the 355 fast tests.
• just test-int runs harness parser, SDK/process lifecycle, and launcher checks.
• just test-e2e selects both pinned hosts by default: OpenCode v1 1.18.34 and v2 2.0.15. Optional host selectors, inferred temporary paths, and local path-only settings are supported.
• PR jobs verify cache-installed plugin artifacts, exact prompt editing results, provider-free startup, and a no-plugin negative control. Failures retain narrowly scoped synthetic evidence.

Host and driver processes use isolated state, bounded requests, and owned-process cleanup. The private Terminal Control 1.2.1 lifecycle boundary and current validation limits are documented in docs/test-e2e.md.

Validation

Validated on macOS arm64:

• just check: lint and 355 fast tests passed.
• just test-int: 24 harness checks passed.
• just compat-unit: 16 tests passed.
• Both pinned hosts: 8 E2E cases passed with the verified v2 binary override; each host recorded 25 passing checkpoints, 17 verified package files, provider-free startup, and no cleanup errors.
• Strict harness TypeScript, actionlint, and independent review passed.

Ubuntu CI passed on commit 88a7fc8: check, Harness integration tests, E2E tests (v1), and E2E tests (v2). Both E2E jobs also passed their no-plugin negative controls.

Notes and follow-up

• Automatic v2 bootstrap was blocked locally by npm registry ENOTCONN; the verified native-binary override passed. CI provisions its pinned hosts explicitly.
• .env.template is included for optional local path settings. Local .env files remain ignored and are not committed.

No product-source or existing Python compatibility-harness changes are included. Required-status branch protection is a separate owner action after the new checks run successfully.