feat(KB-185): add global/project settings hierarchy with scope-aware UI

- Add GlobalSettingsStore with file-based storage in ~/.pi/kb/settings.json
- Implement two-tier hierarchy: global (user prefs) and project (.kb/config.json)
- Update TaskStore to merge settings with project overriding global
- Add API endpoints: GET/PUT /api/settings/global and GET /api/settings/scopes
- Add scope indicators (🌐 global, 📁 project) to settings modal sidebar
- Implement scope-aware save: only save active scope, reject global-only fields
- Add frontend API functions for global settings operations
- Add tests for GlobalSettingsStore, settings routes, and SettingsModal scopes
- Create changeset for the new settings hierarchy feature
- Update AGENTS.md with settings hierarchy documentation

packages/dashboard/app/api.ts

@@ -7,6 +7,8 @@ import type {
   Column,
   MergeResult,
   Settings,
+  GlobalSettings,
+  ProjectSettings,
   BatchStatusResult,
   BatchStatusResponse,
   BatchStatusEntry,
@@ -198,6 +200,24 @@ export function updateSettings(settings: Partial<Settings>): Promise<Settings> {
   });
 }
 
+/** Fetch global (user-level) settings from ~/.pi/kb/settings.json */
+export function fetchGlobalSettings(): Promise<GlobalSettings> {
+  return api<GlobalSettings>("/settings/global");
+}
+
+/** Update global (user-level) settings. These persist across all kb projects. */
+export function updateGlobalSettings(settings: Partial<GlobalSettings>): Promise<Settings> {
+  return api<Settings>("/settings/global", {
+    method: "PUT",
+    body: JSON.stringify(settings),
+  });
+}
+
+/** Fetch settings separated by scope: { global, project } */
+export function fetchSettingsByScope(): Promise<{ global: GlobalSettings; project: Partial<ProjectSettings> }> {
+  return api<{ global: GlobalSettings; project: Partial<ProjectSettings> }>("/settings/scopes");
+}
+
 export function testNtfyNotification(): Promise<{ success: boolean }> {
   return api<{ success: boolean }>("/settings/test-ntfy", {
     method: "POST",