Add stack Update, ComfyUI model manager, and slim ComfyUI stack.

Server UI gains Update on stack cards, ComfyUI Models tab with workflow
scan and downloads, and centralized comfyui_config. Model catalog and
download scripts move from stacks/comfyui to server-ui so ComfyUI stays a
minimal Docker wrapper for easier image updates.

stacks/server-ui/compose_runner.py

@@ -230,6 +230,14 @@ def _parse_stacks_yaml_simple(text: str) -> dict[str, Any]:
     return {"stacks": stacks}
 
 
+def find_compose_file(stack_dir: Path) -> Path | None:
+    for name in ("compose.yaml", "docker-compose.yml", "docker-compose.yaml"):
+        path = stack_dir / name
+        if path.is_file():
+            return path
+    return None
+
+
 def _run_compose(
     stack: StackConfig,
     *args: str,
@@ -240,10 +248,17 @@ def _run_compose(
         "compose",
         "--project-directory",
         stack.compose_dir,
-        "--profile",
-        stack.profile,
-        *args,
     ]
+    compose_file = find_compose_file(stack.path)
+    if compose_file is not None:
+        cmd.extend(["-f", str(compose_file)])
+    cmd.extend(
+        [
+            "--profile",
+            stack.profile,
+            *args,
+        ]
+    )
     return subprocess.run(
         cmd,
         capture_output=True,
@@ -389,6 +404,36 @@ def stack_recreate(stack: StackConfig) -> str:
     return (proc.stdout + proc.stderr).strip()
 
 
+def stack_update(stack: StackConfig) -> str:
+    state = get_container_state(stack)
+    was_running = state["running"]
+
+    pull = _run_compose(stack, "pull", timeout=600)
+    if pull.returncode != 0:
+        raise ComposeError(
+            pull.stderr.strip() or pull.stdout.strip() or "pull failed",
+            pull.returncode,
+            pull.stderr,
+        )
+    output = (pull.stdout + pull.stderr).strip()
+
+    if not was_running:
+        suffix = "\n[server-ui] Obraz pobrany. Stack zatrzymany — użyj Start."
+        return (output + suffix).strip() if output else suffix.strip()
+
+    proc = _run_compose(stack, "up", "-d", "--force-recreate", timeout=300)
+    if proc.returncode != 0:
+        raise ComposeError(
+            proc.stderr.strip() or proc.stdout.strip() or "recreate failed",
+            proc.returncode,
+            proc.stderr,
+        )
+    recreate_out = (proc.stdout + proc.stderr).strip()
+    if recreate_out:
+        output = f"{output}\n{recreate_out}".strip() if output else recreate_out
+    return output
+
+
 def set_stack_port(
     stack: StackConfig,
     port: int,