ci: use packaged dist/index.js for host e2e instead of raw TS source

Smoke workflow `smoke-opencode-linux.yml` (just added) proved that
opencode-on-Linux is healthy in isolation: both curl and bun's fetch
reach /doc in seconds with either 127.0.0.1 or 0.0.0.0 binding. So
the host e2e hang is NOT a Linux opencode bug.

The remaining structural difference between smoke (~10s spawn-to-OK)
and host e2e (~5min timeout) is plugin loading. Host e2e was pointing
opencode at `packages/plugin/src/index.ts` — raw TypeScript source
spanning hundreds of submodule imports. Bun's runtime TS transpile +
dynamic resolution can be slow on cold Linux runners.

Production never loads from src/ — published users get a single
bundled `dist/index.js`. Testing src/ exposes us to a slowness path
real users never see. CI workflows already build dist before host
e2e, so the file is available; the harness just wasn't using it.

Resolution: prefer `packages/plugin/dist/index.js` when it exists,
fall back to `src/` only when running locally without a build (which
also avoids breaking local devs who haven't built).

Author: ualtinok

packages/e2e-tests/src/opencode-runner/spawn.ts

@@ -8,12 +8,22 @@
  */
 
 import { type ChildProcess, spawn } from "node:child_process";
-import { mkdirSync, writeFileSync } from "node:fs";
+import { existsSync, mkdirSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join, resolve } from "node:path";
 
 const REPO_ROOT = resolve(import.meta.dir, "../../../..");
-const PLUGIN_ENTRY = join(REPO_ROOT, "packages/plugin/src/index.ts");
+// Prefer the bundled `dist/index.js` (what published users actually run)
+// over raw `src/index.ts`. The bundled file is one ~5MB file with all imports
+// inlined; loading it is fast even on cold runners. The TS-source path
+// triggers Bun's runtime TS transpile + dynamic resolution across hundreds
+// of submodule imports — on slow Linux CI runners this can take long enough
+// to make `opencode serve` appear hung when it's just blocked in plugin
+// load. Production never loads from src/, so testing src/ doesn't reflect
+// reality and exposes us to a slowness path users never see.
+const PLUGIN_DIST_ENTRY = join(REPO_ROOT, "packages/plugin/dist/index.js");
+const PLUGIN_SRC_ENTRY = join(REPO_ROOT, "packages/plugin/src/index.ts");
+const PLUGIN_ENTRY = existsSync(PLUGIN_DIST_ENTRY) ? PLUGIN_DIST_ENTRY : PLUGIN_SRC_ENTRY;
 
 export interface IsolatedEnv {
     configDir: string;