feat: add comprehensive scenario-based test suite

- 6 deterministic scenarios: session overflow, concurrent read/write,
  TTL expiry, persistence recovery, store lifecycle, hot key thundering herd
- 3 randomized scenarios: mixed workload, burst writes, concurrent multi-store
- Randomized tests log seed for reproducibility (SCENARIO_SEED env var)
- Added to CI workflow (runs on every push)
- Added to comprehensive test workflow (runs daily)

Author: rishabhverma17

.github/workflows/ci.yml

@@ -88,6 +88,28 @@ jobs:
           test-results/
           coverage.html
 
+  scenario-tests:
+    name: Scenario Tests
+    runs-on: ubuntu-latest
+    needs: unit-tests
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+
+    - name: Set up Go
+      uses: actions/setup-go@v5
+      with:
+        go-version: ${{ env.GO_VERSION }}
+
+    - name: Download dependencies
+      run: go mod download
+
+    - name: Run scenario tests
+      run: |
+        go test -v -race -timeout=5m ./tests/scenarios/...
+        echo "✅ Scenario tests completed"
+
   integration-tests:
     name: Integration Tests (Newman)
     runs-on: ubuntu-latest

.github/workflows/test-comprehensive.yml

@@ -109,3 +109,21 @@ jobs:
       with:
         name: benchmark-results
         path: benchmark-results/
+
+  scenario-tests:
+    name: Scenario Tests (Real-World Patterns)
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-go@v5
+      with:
+        go-version: ${{ env.GO_VERSION }}
+    - run: go mod download
+    - name: Run deterministic scenarios
+      run: |
+        go test -v -race -timeout=5m -run 'Test(SessionStoreOverflow|ConcurrentReadWrite|TTLExpiry|PersistenceRecovery|StoreLifecycle|HotKeyThunderingHerd)' \
+          ./tests/scenarios/...
+    - name: Run randomized scenarios
+      run: |
+        go test -v -race -timeout=5m -run 'TestRandomized' \
+          ./tests/scenarios/...