ci: install the geo extra so location tests match a real install

Tests (all four Python versions) failed on
test_over_budget_same_state_omits_prefix while passing locally. Root
cause: CI installed only ".[test]", leaving out the optional geo extra
(us, pycountry). normalize_us_state() returns (None, None) when `us` is
absent, so "Washington" no longer normalizes to "WA" and the AQI
prefix-budget path wrongly concluded the resolved state differed from
default_state, keeping the "Seattle, WA: " prefix.

Install ".[test,geo]" in both the test matrix and the mypy job. This
also un-skips ~27 geo-dependent tests that were silently skipping in CI
and which pass with the extra present.

Also ignore _debug/, a local scratch directory for captured configs and
logs that should never be committed.

.github/workflows/test.yml

@@ -100,7 +100,7 @@ jobs:
       - name: Install dependencies
         run: |
           pip install --upgrade pip
-          pip install -e ".[test]"
+          pip install -e ".[test,geo]"
           pip install mypy
 
       - name: mypy — strict overrides on typed modules
@@ -152,7 +152,10 @@ jobs:
       - name: Install dependencies
         run: |
           pip install --upgrade pip
-          pip install -e ".[test]"
+          # `geo` (us, pycountry) is optional at runtime but drives US state and
+          # country normalization; without it ~27 location tests skip and the AQI
+          # prefix-budget behavior silently differs from a real install.
+          pip install -e ".[test,geo]"
 
       - name: Run tests with coverage
         run: pytest tests/ -v --tb=short