fix(ci): install uv via official installer in tradein test job (PEP 668)

The #666 pytest gate's 'Install uv' step used `pip install uv`, which fails
on the ubuntu-latest runner with PEP 668 externally-managed-environment →
the test job errored → build+deploy skipped (deploy blocked). Switch to the
official standalone installer (curl astral.sh/uv/install.sh) + $GITHUB_PATH.
pytest itself is green locally (1087 passed); this was purely the runner uv
install. Unblocks deploy-tradein.yml.

.forgejo/workflows/deploy-tradein.yml

@@ -62,7 +62,11 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install uv
-        run: pip install --no-cache-dir uv
+        # Официальный standalone-инсталлер: системный `pip install uv` на
+        # ubuntu-runner падает с PEP 668 externally-managed-environment (#666 CI).
+        run: |
+          curl -LsSf https://astral.sh/uv/install.sh | sh
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
 
       - name: Sync deps (incl. dev group — pytest)
         run: uv sync --frozen