chore: allow manual nightly-tests pipeline run

.drone.yml

@@ -187,6 +187,7 @@ name: nightly-tests
 trigger:
   event:
     - cron
+    - custom  # Allows manual triggering
   cron:
     - "0 2 * * *"  # Run at 2 AM daily
 

docs/test-optimization-summary.md

@@ -172,7 +172,12 @@ just test-all --max-failures 5
 
 - **Standard CI:** Runs `mix test --exclude slow` for faster feedback loops
 - **Nightly Builds:** Separate pipeline (`nightly-tests`) runs daily at 2 AM and executes all performance tests
-- **Manual Execution:** Performance tests can be executed anytime with `just test-slow`
+- **Manual Execution:** 
+  - **Local:** Performance tests can be executed anytime with `just test-slow`
+  - **CI:** The nightly pipeline can be manually triggered via Drone CLI or Web UI:
+    ```bash
+    drone build start <owner>/<repo> <branch> --event custom
+    ```
 
 ### Further Details
 

docs/test-slow-suite.md

@@ -134,6 +134,26 @@ just test-all --max-failures 5
 - Executes daily at 2 AM via cron trigger
 - Pipeline name: `nightly-tests`
 
+**Manual Execution:**
+
+The nightly pipeline can be manually triggered using:
+
+**Drone CLI:**
+```bash
+drone build start <owner>/<repo> <branch> --event custom
+```
+
+**Drone Web UI:**
+- Navigate to the repository in Drone
+- Go to the `nightly-tests` pipeline
+- Click "Run" or "Restart" and select event type `custom`
+
+**Example:**
+```bash
+# Trigger nightly-tests pipeline manually
+drone build start local-it/mitgliederverwaltung main --event custom
+```
+
 ---
 
 ## Best Practices for New Performance Tests