test: add pytest suite and gate Docker builds on it

Unit tests cover the SQL gate, broadcast codec, Hive writer layout,
and flight kinematics. CI runs pytest first; the simulator image build
runs tests in a dedicated stage before the final layer.

.github/workflows/release.yaml

@@ -30,6 +30,10 @@ jobs:
       - name: Install dependencies
         run: pip install --quiet -r simulator/requirements.txt
 
+      - name: Unit tests (TDD gate)
+        working-directory: simulator
+        run: pytest tests/ -q
+
       - name: Compile check
         run: python -m compileall -q simulator/virtual_drone simulator/monitoring simulator/explorer
 
@@ -49,26 +53,6 @@ jobs:
           print(f"smoke flight OK: {rows} telemetry rows")
           EOF
 
-      - name: SQL gate tests
-        working-directory: simulator
-        run: |
-          python - <<'EOF'
-          import sys
-          sys.path.insert(0, "explorer")
-          from server import gate
-
-          assert gate("SELECT 1") is None
-          assert gate("WITH t AS (SELECT 1) SELECT * FROM t") is None
-          assert gate("DESCRIBE telemetry") is None
-          assert gate("DROP TABLE telemetry") is not None
-          assert gate("SELECT 1; SELECT 2") is not None
-          assert gate("INSTALL httpfs") is not None
-          assert gate("SET memory_limit='1GB'") is not None
-          assert gate("/* sneaky */ COPY t TO 'x'") is not None
-          assert gate("") is not None
-          print("SQL gate OK: reads pass, writes and config are rejected")
-          EOF
-
   scan:
     name: Trivy scan
     runs-on: ubuntu-latest
@@ -141,6 +125,7 @@ jobs:
           TAG="${{ steps.version.outputs.new_tag }}"
           mkdir -p .tmp
           tar --exclude='.git' --exclude='.tmp' --exclude='simulator/data' \
+              --exclude='var/t1' --exclude='var/t3' \
               --exclude='simulator/.venv' --exclude='prototype/node_modules' \
               -czf ".tmp/swarm-house-${TAG}.tar.gz" .