feat(ui): complete Plan 06-01 - fix model scan + move model selector to input

- Fix Rust model scan to only list top-level models (not subdirectories)
- Add scan_model_dir_top_level() function in model_files.rs
- Create ModelSelectorPill component for chat input area
- Remove model-section from Sidebar, move to ChatView
- Update ChatView props to receive model-related props
- Update tests for new ChatView props

tauri-app/src/components/ModelSelectorPill.tsx

@@ -0,0 +1,102 @@
+import { useState, useRef, useEffect } from "react";
+import { ChevronDown, Loader2 } from "lucide-react";
+import type { ModelInfo, ServerStatus } from "../lib/types";
+import type { RuntimeModelFile } from "../features/runtime/types";
+import { getDisplayName, isInChatSelector } from "../lib/modelAlias";
+
+interface ModelSelectorPillProps {
+  models: ModelInfo[];
+  localModels: RuntimeModelFile[];
+  selectedModel: string;
+  onModelChange: (id: string) => void;
+  onModelSwap?: (path: string) => void;
+  isSwapping?: boolean;
+  status: ServerStatus;
+}
+
+export default function ModelSelectorPill({
+  models,
+  localModels,
+  selectedModel,
+  onModelChange,
+  onModelSwap,
+  isSwapping,
+  status,
+}: ModelSelectorPillProps) {
+  const [dropdownOpen, setDropdownOpen] = useState(false);
+  const dropdownRef = useRef<HTMLDivElement>(null);
+
+  useEffect(() => {
+    if (!dropdownOpen) return;
+    const handleClickOutside = (e: MouseEvent) => {
+      if (dropdownRef.current && !dropdownRef.current.contains(e.target as Node)) {
+        setDropdownOpen(false);
+      }
+    };
+    document.addEventListener("mousedown", handleClickOutside);
+    return () => document.removeEventListener("mousedown", handleClickOutside);
+  }, [dropdownOpen]);
+
+  const handleSelectModel = (modelId: string) => {
+    setDropdownOpen(false);
+    onModelChange(modelId);
+    if (onModelSwap) {
+      onModelSwap(modelId);
+    }
+  };
+
+  // Unified model list: merge API models + local scanned files
+  const allAvailableModels = [
+    ...models.map((m) => ({ id: m.id, label: getDisplayName(m.id) })),
+    ...localModels.map((m) => ({ id: m.path, label: getDisplayName(m.path) })),
+  ];
+  // Deduplicate by id
+  const seen = new Set<string>();
+  const dedupedModels = allAvailableModels.filter((m) => {
+    if (seen.has(m.id)) return false;
+    seen.add(m.id);
+    return true;
+  });
+
+  // Chat selector: only Cooper + Iron (Steel is settings-only)
+  const chatSelectorModels = dedupedModels.filter((m) => isInChatSelector(m.id));
+
+  const selectedLabel = getDisplayName(selectedModel) || "No model";
+
+  return (
+    <div className="model-selector-pill-wrapper" ref={dropdownRef}>
+      <button
+        type="button"
+        className="model-selector-pill"
+        onClick={() => setDropdownOpen(!dropdownOpen)}
+        disabled={chatSelectorModels.length === 0 || isSwapping}
+        title={chatSelectorModels.length === 0 ? "Start server to load models" : ""}
+        aria-label="Choose active model"
+        aria-expanded={dropdownOpen}
+      >
+        <span className={`model-status-dot status-${status}`} aria-hidden="true" />
+        {isSwapping ? (
+          <Loader2 size={12} strokeWidth={2} className="animate-spin" />
+        ) : (
+          <span className="model-selector-label">{selectedLabel}</span>
+        )}
+        <ChevronDown size={12} strokeWidth={2} className="model-selector-chevron" />
+      </button>
+      {dropdownOpen && (
+        <ul className="model-selector-menu" role="listbox">
+          {chatSelectorModels.map((m) => (
+            <li
+              key={m.id}
+              role="option"
+              aria-selected={m.id === selectedModel}
+              className={`model-selector-item${m.id === selectedModel ? " model-selector-item--selected" : ""}`}
+              onClick={() => handleSelectModel(m.id)}
+            >
+              {m.label}
+            </li>
+          ))}
+        </ul>
+      )}
+    </div>
+  );
+}