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/models/job_log.py

@@ -0,0 +1,17 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, Text, func
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.models.base import Base
+
+
+class JobLog(Base):
+    __tablename__ = "job_logs"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    job_id: Mapped[int] = mapped_column(ForeignKey("print_jobs.id"))
+    message: Mapped[str] = mapped_column(Text)
+    created_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())
+
+    job: Mapped["PrintJob"] = relationship(back_populates="logs")