feat(11-04): add GET /clients/{id} route and client_detail.html template

- Add client_detail route in pages.py with 404 on unknown client_id
- Build grouped dict {client.name: [printers]} for printer_list partial reuse
- Pass clients + driver_data for edit modal compatibility
- Create client_detail.html extending base.html, includes printer_list partial

imptune/api/pages.py

@@ -156,6 +156,44 @@ def clients_page(request: Request):
     )
 
 
+@router.get("/clients/{client_id}", response_class=HTMLResponse)
+def client_detail(request: Request, client_id: int):
+    from imptune.db.models import Client, Driver, Printer
+
+    client = Client.get_or_none(Client.id == client_id)
+    if client is None:
+        return HTMLResponse(
+            content="<h1>404 Not Found</h1><p>Client not found.</p>",
+            status_code=404,
+        )
+
+    query = (
+        Printer.select(Printer, Client)
+        .join(Client, JOIN.LEFT_OUTER)
+        .where(Printer.client == client_id)
+        .order_by(Printer.name)
+    )
+    grouped = {client.name: list(query)}
+
+    clients = list(Client.select().order_by(Client.name))
+    all_drivers = list(Driver.select().order_by(Driver.uploaded_at.desc()))
+    driver_data = [
+        {"driver": d, "names": json.loads(d.driver_desc) if d.driver_desc else []}
+        for d in all_drivers
+    ]
+
+    return templates.TemplateResponse(
+        request=request,
+        name="client_detail.html",
+        context={
+            "client": client,
+            "grouped": grouped,
+            "clients": clients,
+            "driver_data": driver_data,
+        },
+    )
+
+
 @router.get("/packages", response_class=HTMLResponse)
 def packages_page(request: Request):
     from imptune.db.models import Client, Driver, Printer

imptune/templates/client_detail.html

@@ -0,0 +1,11 @@
+{% extends "base.html" %}
+
+{% block content %}
+<h1>{{ client.name }}</h1>
+<p><a href="/clients">&larr; All Clients</a></p>
+
+<section>
+  <h2>Printers</h2>
+  {% include "partials/printer_list.html" %}
+</section>
+{% endblock %}