Run server tests on Linux+Windows matrix (#809)

* Run server tests on Linux+Windows matrix

Replace the hand-curated Windows server test allow-list with a full-suite matrix run.\nBoth Ubuntu and Windows now run the same server test command with shared setup and secrets.

* Add isPlatform helper and gate Windows-hostile server tests

- Add a shared server test isPlatform helper.

- Migrate existing Windows-gated spawn, worktree, executable, and worktree-core tests to the helper.

- Gate Windows-hostile symlink, macOS path-normalization, and POSIX shell setup tests with skipIf.

* Replace POSIX shell calls in test fixtures with Node primitives

- Replaced test fixture mkdir/echo shell setup with fs mkdirSync/writeFileSync calls in touched server tests.

- Replaced git shell strings with execFileSync/spawnSync argv calls across checkout, worktree, MCP, script, and workspace git fixtures.

- Gated the directory suggestion symlink escape tests on Windows because those fixtures require POSIX symlink behavior.

* Fix Windows server-test failures and split POSIX-only suites into sibling files

- Fix Windows path/cwd assertions in terminal, session/workspace, git-service, checkout-git, MCP, logger, spawn, and registry bootstrap tests.\n- Keep terminal tests runnable on Windows by canonicalizing temp cwd fixtures and ensuring a Windows shell fallback.\n- Gate POSIX-only shell, signal, Unix socket, and git-worktree reuse fixtures that need dedicated Windows coverage later.

* Move POSIX-only test blocks into sibling .posix.test.ts files

- terminal.test.ts: moved PTY/bash interaction blocks into terminal.posix.test.ts.

- worktree.test.ts: moved git-worktree and teardown shell blocks into worktree.posix.test.ts.

- worktree-bootstrap.test.ts: moved setup shell and terminal-backed service blocks into worktree-bootstrap.posix.test.ts.

- worktree-core.test.ts: moved the POSIX-only worktree-core suite into worktree-core.posix.test.ts and removed the empty original.

- provider-availability.test.ts and file-explorer/service.test.ts: moved POSIX PATH/symlink blocks into sibling suites.

* Fix Windows 8.3 short-name, EBUSY cleanup, and node-pty shell-path failures in server tests

- Normalize temp home directories in directory suggestion assertions to avoid Windows short-name mismatches.

- Use Windows-valid terminal shells/cwds in terminal fixtures and wait for terminal-manager PTYs before cleanup.

- Replace hardcoded POSIX paths in workspace-git/MCP/loop fixtures with platform-resolved paths or command files.

- Gate the two explicitly Linux-only workspace-git watcher tests.

* Replace hardcoded POSIX paths with portable Node path constructions in server tests

- checkout-git.test.ts and worktree-session.test.ts: compare Windows temp paths with realpathSync.native to avoid 8.3 short-name mismatches.

- directory-suggestions.test.ts: canonicalize result and expected paths with realpathSync.native.

- session.workspaces.test.ts: replace literal /tmp and /Users fixtures with path.resolve/path.join constructions.

- workspace-git-service.primitive.test.ts, loop-service.test.ts, and mcp-server.test.ts: use canonical repo/temp paths and shell-safe relative verify commands.

* Fix loop-service verify-check shell and workspace-git-service path-separator on Windows

- Run the loop-service verify script through the current Node executable with a relative script path.

- Normalize the workspace-git-service expected repo cwd to forward slashes for the listWorktrees assertion.

* Fix loop-service worker PTY spawn on Windows

- Canonicalize the loop-service temporary root and workspace with realpathSync.native before worker agents use the path as cwd.

* Gate loop-service real-worker-PTY test on Windows

- Skip the real worker PTY loop test on Windows after ConPTY path resolution still fails with node-pty error 267.\n- Keep the test running on POSIX so the loop behavior remains covered.

* Stub getMetricsSnapshot in test mocks to suppress async-leak uncaught exceptions on Windows

- Add a no-op AgentManager metrics snapshot to the WebSocket notification test server stub.

* Fix terminal-manager Windows-path test to avoid PTY spawn into nonexistent dir

- Use an existing temporary cwd for the createTerminal absolute-path validation assertion so node-pty does not spawn into a missing Windows directory.

packages/server/src/utils/checkout-git-batching.test.ts

@@ -1,5 +1,5 @@
-import { execSync } from "node:child_process";
-import { mkdtempSync, rmSync, writeFileSync, realpathSync } from "node:fs";
+import { execFileSync } from "node:child_process";
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync, realpathSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { beforeEach, afterEach, describe, expect, it, vi } from "vitest";
@@ -38,16 +38,18 @@ function initRepoWithTrackedChanges(fileCount: number): { tempDir: string; repoD
   const tempDir = realpathSync(mkdtempSync(join(tmpdir(), "checkout-git-batch-test-")));
   const repoDir = join(tempDir, "repo");
 
-  execSync(`mkdir -p ${repoDir}`);
-  execSync("git init -b main", { cwd: repoDir });
-  execSync("git config user.email 'test@test.com'", { cwd: repoDir });
-  execSync("git config user.name 'Test'", { cwd: repoDir });
+  mkdirSync(repoDir, { recursive: true });
+  execFileSync("git", ["init", "-b", "main"], { cwd: repoDir });
+  execFileSync("git", ["config", "user.email", "test@test.com"], { cwd: repoDir });
+  execFileSync("git", ["config", "user.name", "Test"], { cwd: repoDir });
 
   for (let i = 0; i < fileCount; i += 1) {
     writeFileSync(join(repoDir, `file-${i}.txt`), `before-${i}\n`);
   }
-  execSync("git add .", { cwd: repoDir });
-  execSync("git -c commit.gpgsign=false commit -m 'initial'", { cwd: repoDir });
+  execFileSync("git", ["add", "."], { cwd: repoDir });
+  execFileSync("git", ["-c", "commit.gpgsign=false", "commit", "-m", "initial"], {
+    cwd: repoDir,
+  });
 
   for (let i = 0; i < fileCount; i += 1) {
     writeFileSync(join(repoDir, `file-${i}.txt`), `after-${i}\n`);