Add job creation with UUID, STL upload/library, search, job log, TZ, and CLAUDE.md

- PrintJob: job_uuid (UUID4), customer, logs relationship
- JobLog model + migration 0004 (also includes job_logs table)
- POST /jobs: upload STL or select from library, auto-logs 'Job created'
- GET /jobs?q=: search by customer or filename across all statuses
- app/stl.py: STL_UPLOAD_DIR helper (from env, default /data/stl)
- docker-compose: named volume stl_files mounted at /data/stl
- .env.install: added STL_UPLOAD_DIR and TZ=Europe/Berlin
- CLAUDE.md: full project context for future sessions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/stl.py

@@ -0,0 +1,20 @@
+import os
+from pathlib import Path
+
+_SUPPORTED = {".stl", ".3mf", ".gcode"}
+
+
+def get_stl_dir() -> Path:
+    d = Path(os.environ.get("STL_UPLOAD_DIR", "/data/stl"))
+    d.mkdir(parents=True, exist_ok=True)
+    return d
+
+
+def list_stl_files() -> list[str]:
+    try:
+        return sorted(
+            f.name for f in get_stl_dir().iterdir()
+            if f.suffix.lower() in _SUPPORTED
+        )
+    except FileNotFoundError:
+        return []