feat(03-02): implement printer detail page with driver info and regenerate placeholder

- Add GET /printers/{printer_id} route to pages.py with LEFT OUTER JOINs on Client and Driver
- Create printer_detail.html full-page template showing all config fields and driver info
- Display "No driver assigned" when driver FK is null
- Add disabled "Regenerate Package" button (Phase 4 placeholder)
- Make printer names in printer_list.html clickable links to detail page

imptune/api/pages.py

@@ -7,6 +7,7 @@ from fastapi.responses import HTMLResponse
 from fastapi.templating import Jinja2Templates
 from peewee import JOIN
 
+
 router = APIRouter()
 
 templates = Jinja2Templates(directory=str(Path(__file__).parent.parent / "templates"))
@@ -73,6 +74,35 @@ def printers_page(request: Request):
     )
 
 
+@router.get("/printers/{printer_id}", response_class=HTMLResponse)
+def printer_detail(request: Request, printer_id: int):
+    from imptune.db.models import Client, Driver, Printer
+
+    printer = (
+        Printer.select(Printer, Client, Driver)
+        .join(Client, JOIN.LEFT_OUTER)
+        .switch(Printer)
+        .join(Driver, JOIN.LEFT_OUTER)
+        .where(Printer.id == printer_id)
+        .first()
+    )
+    if printer is None:
+        return HTMLResponse(
+            content="<h1>404 Not Found</h1><p>Printer not found.</p>",
+            status_code=404,
+        )
+
+    driver_names: list[str] = []
+    if printer.driver_id and printer.driver.driver_desc:
+        driver_names = json.loads(printer.driver.driver_desc)
+
+    return templates.TemplateResponse(
+        request=request,
+        name="printer_detail.html",
+        context={"printer": printer, "driver_names": driver_names},
+    )
+
+
 @router.get("/clients", response_class=HTMLResponse)
 def clients_page(request: Request):
     from imptune.db.models import Client