Speed up server CI tests (#2537)

* perf(ci): reduce server test latency

Server test files use isolated resources, so they do not require suite-wide serialization.

* fix(ci): scope server test parallelism to unit suite

Keep real-provider and local-resource suites serialized because they may share user configuration and account limits.

* fix(terminal): isolate zsh runtimes by process

Prevent concurrent daemon and test processes from deleting or replacing shell integration files used by another process.

* fix(ci): preserve required matrix check names

GitHub evaluates job conditions before expanding a matrix. Expand active matrices first and gate their expensive steps so required check contexts are always reported. Allow superseded runs to cancel while retaining fail-open path detection.

packages/server/package.json

@@ -49,7 +49,7 @@
     "speech:download": "tsx scripts/download-speech-models.ts",
     "speech:transcribe:local": "tsx scripts/transcribe-local-wav.ts",
     "test": "npm run test:unit && npm run test:integration",
-    "test:unit": "vitest run --exclude \"**/*.e2e.test.ts\"",
+    "test:unit": "vitest run --fileParallelism --exclude \"**/*.e2e.test.ts\"",
     "test:integration": "vitest run --maxWorkers=1 src/server/daemon-e2e/models.e2e.test.ts src/server/daemon-e2e/live-preferences.e2e.test.ts src/server/agent/model-catalog.e2e.test.ts",
     "test:integration:all": "npm run test:e2e",
     "test:integration:real": "vitest run real.e2e.test.ts",