Complete frontend migration to unified Pi harness (Phase 7 + Phase 9)

- Delete legacy hooks: useClaude.ts, useOpenCode.ts, usePiMono.ts, App.backup.tsx
- Update all components to use usePi instead of legacy hooks
- Replace useVisiblePiMonoModels/useClaudeModels/useOpenCodeModels with useVisiblePiModels
- Migrate from LegacyChatMessage to ChatMessage type throughout
- Update SessionBar to remove provider and archive props
- Simplify ChatDetailPanel to Pi-only (remove Claude/OpenCode components)
- Fix useChatSessions calls (remove provider parameter)
- Update user-settings types: provider now only 'pi' instead of legacy values
- Update PI_HARNESS_REBUILD.md to mark phases complete

src/apps/officer-web/Screens/Dashboard/Settings/ProfileSettings/TaskDefaults.tsx

@@ -12,13 +12,11 @@ import {
   SelectValue,
 } from '@/components/ui/select';
 import { useSettings } from '@/state/useSettings';
-import { useVisibleClaudeModels, useVisibleOpenCodeModels, useVisiblePiMonoModels } from '@/state/useModels';
+import { useVisiblePiModels, type ModelOption } from '@/state/useModels';
 
 export const TaskDefaults = () => {
   const { settings, saveSettings } = useSettings();
-  const claudeModels = useVisibleClaudeModels();
-  const openCodeModels = useVisibleOpenCodeModels();
-  const piMonoModels = useVisiblePiMonoModels();
+  const piModels = useVisiblePiModels();
   const [isSaving, setIsSaving] = useState(false);
 
   const [model, setModel] = useState<string | null>(settings.tasks.defaultModel);
@@ -27,7 +25,7 @@ export const TaskDefaults = () => {
     setModel(settings.tasks.defaultModel);
   }, [settings]);
 
-  const buildGroups = (models: { id: string; name: string; provider?: string }[], fallback: string) => {
+  const buildGroups = (models: ModelOption[], fallback: string) => {
     const groups: Record<string, { id: string; name: string }[]> = {};
     for (const m of models) {
       const provider = m.provider ?? fallback;
@@ -39,17 +37,13 @@ export const TaskDefaults = () => {
       .map(([provider, models]) => ({ provider, models: models.sort((a, b) => a.name.localeCompare(b.name)) }));
   };
 
-  const openCodeGroups = useMemo(() => buildGroups(openCodeModels, 'OpenCode'), [openCodeModels]);
-  const piMonoGroups = useMemo(() => buildGroups(piMonoModels, 'Pi'), [piMonoModels]);
+  const piGroups = useMemo(() => buildGroups(piModels, 'Pi'), [piModels]);
 
   const handleSave = async () => {
     if (isSaving) return;
     setIsSaving(true);
     try {
-      const isPiMono = piMonoModels.some((m) => m.id === model);
-      const isOpenCode = openCodeModels.some((m) => m.id === model);
-      const defaultProvider = isPiMono ? ('pi-mono' as const) : isOpenCode ? ('opencode' as const) : ('claude' as const);
-      await saveSettings({ ...settings, tasks: { defaultProvider, defaultModel: model } });
+      await saveSettings({ ...settings, tasks: { defaultProvider: 'pi', defaultModel: model } });
       toast.success('Task defaults saved');
     } catch {
       toast.error('Failed to save settings');
@@ -67,29 +61,9 @@ export const TaskDefaults = () => {
             <SelectValue placeholder="Same as chat default" />
           </SelectTrigger>
           <SelectContent className="z-[600] max-h-[300px]">
-            {claudeModels.length > 0 && (
-              <SelectGroup>
-                <SelectLabel>Claude</SelectLabel>
-                {claudeModels.map((m) => (
-                  <SelectItem key={m.id} value={m.id}>
-                    {m.name}
-                  </SelectItem>
-                ))}
-              </SelectGroup>
-            )}
-            {openCodeGroups.map(({ provider, models }) => (
-              <SelectGroup key={provider}>
-                <SelectLabel>{provider} (OpenCode)</SelectLabel>
-                {models.map((m) => (
-                  <SelectItem key={`${provider}:${m.id}`} value={m.id}>
-                    {m.name}
-                  </SelectItem>
-                ))}
-              </SelectGroup>
-            ))}
-            {piMonoGroups.map(({ provider, models }) => (
+            {piGroups.map(({ provider, models }) => (
               <SelectGroup key={`pi-${provider}`}>
-                <SelectLabel>{provider} (Pi)</SelectLabel>
+                <SelectLabel>{provider}</SelectLabel>
                 {models.map((m) => (
                   <SelectItem key={`pi:${provider}:${m.id}`} value={m.id}>
                     {m.name}