fix(ci): install only [dev] extras and disable xdist to stop flaky failures

The smoke-and-build job was failing ~62% of runs (5/8) due to:

1. Heavy dependency install: 'uv pip install -e ".[all,dev]"' installed
   ALL optional extras (218+ packages) including compiled/native deps
   like faster-whisper, modal, daytona, voice, messaging libs.
   This is slow and prone to network/timeout failures.

2. Tight timeout: timeout-minutes: 5 was insufficient when the install
   step alone can take 3-4 minutes on a cold cache.

3. Unnecessary xdist parallelism: pytest addopts '-n auto' enabled
   parallel test execution even for a single E2E test, adding overhead
   and potential resource contention on CI runners.

Fixes:
- Install only '.[dev]' — smoke tests already skip on missing deps,
  and E2E test only needs core project + pytest.
- Increase timeout-minutes from 5 to 10 for headroom.
- Add '-p no:xdist' to pytest command to disable xdist parallelism
  in CI (avoids worker spawn overhead for single-file test runs).

.gitea/workflows/ci.yml

@@ -13,7 +13,7 @@ concurrency:
 jobs:
   smoke-and-build:
     runs-on: ubuntu-latest
-    timeout-minutes: 5
+    timeout-minutes: 10
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
@@ -31,7 +31,7 @@ jobs:
         run: |
           uv venv .venv --python 3.11
           source .venv/bin/activate
-          uv pip install -e ".[all,dev]"
+          uv pip install -e ".[dev]"
 
       - name: Smoke tests
         run: |
@@ -55,7 +55,7 @@ jobs:
       - name: Green-path E2E
         run: |
           source .venv/bin/activate
-          python -m pytest tests/test_green_path_e2e.py -q --tb=short
+          python -m pytest tests/test_green_path_e2e.py -q --tb=short -p no:xdist
         env:
           OPENROUTER_API_KEY: ""
           OPENAI_API_KEY: ""