test(js-sdk): run the template test suite on Bun (#1600)

## Description

Adds `--project template` to `test:bun` so the Bun CI leg runs the
template suite, matching the Deno leg (#1595).

No code changes are needed: the template suite previously failed under
Bun because Bun's JavaScriptCore elides tail-call frames and the
fixed-depth stack walk attributed build errors one frame past the user's
call site (the workaround attempt in #1596 was closed in favor of
#1599). With #1599's boundary-based frame selection (now merged), the
suite passes under Bun as-is.

The CI workflow already passes `E2B_API_KEY`/`E2B_DOMAIN` to the Bun
leg, and the matrix comment (updated in #1595) already covers Bun
re-running API-backed suites, so `package.json` is the only change.

## Testing

Full `test:bun` (unit + connectionConfig + template) green locally on
Bun 1.3.14 against the real API: 530 passed, 35 skipped, 0 failed —
including all 34 stack-trace/caller-directory tests that pin exact user
call-site line/columns, the frames Bun used to elide.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: mishushakov

packages/js-sdk/package.json

@@ -36,7 +36,7 @@
     "generate:mcp": "json2ts -i ./../../spec/mcp-server.json -o src/sandbox/mcp.d.ts --unreachableDefinitions --style.singleQuote --no-style.semi",
     "check-deps": "knip",
     "pretest": "npx playwright install --with-deps chromium",
-    "test:bun": "bunx --bun vitest run --project unit --project connectionConfig",
+    "test:bun": "bunx --bun vitest run --project unit --project connectionConfig --project template",
     "test:cf": "vitest run --config tests/runtimes/cloudflare/vitest.config.mts",
     "test:cf:deploy": "vitest run --config tests/runtimes/cloudflare-deploy/vitest.config.mts",
     "test:deno": "deno run -A npm:vitest run --project unit --project connectionConfig --project template",