Stop uv run undoing the coverage-only install

uv run syncs the project environment first, so the 75 packages that
--only-group coverage had just skipped came straight back in the next step:
"Installed 1 package" followed by "Installed 75 packages". --no-sync keeps the
environment the previous step built.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: lukeshingles

.github/workflows/test.yml

@@ -127,11 +127,12 @@ jobs:
                   pattern: coverage-data-*
                   merge-multiple: true
 
+            # --no-sync or uv run reinstalls the default groups it was just told to skip
             - name: Combine coverage and report
               run: |
-                  uv run coverage combine
-                  uv run coverage xml
-                  uv run coverage report
+                  uv run --no-sync coverage combine
+                  uv run --no-sync coverage xml
+                  uv run --no-sync coverage report
 
             - name: Check for a pull request associated with this commit
               id: haspr