refactor: consolidate loading/error states and extract instance actions hook

Frontend:
- Create reusable DataStates components (LoadingState, ErrorState, EmptyState)
- Refactor 12 pages to use shared state components instead of inline JSX
- Extract useInstanceActions hook to eliminate session action duplication
- Update dashboard and sessions pages to use shared hook

OpenSpec:
- Archive completed mobile-app-usability change (44/44 tasks)
- Archive completed add-config-profiles change (15/15 tasks)

Quality: TypeScript check passes, production build succeeds

apps/web/src/pages/config-profiles.tsx

@@ -1,4 +1,5 @@
 import { useCallback, useEffect, useState } from "react";
+import { EmptyState, ErrorState, LoadingState } from "../components/data-states";
 import { Icon } from "../components/icon";
 import { useMobileViewport } from "../hooks/use-mobile-viewport";
 import { extractErrorMessage } from "../utils/errors";
@@ -408,7 +409,7 @@ export const ConfigProfilesPage = () => {
   if (status === "loading") {
     return (
       <div className="container">
-        <p>Loading Config Profiles...</p>
+        <LoadingState message="Loading Config Profiles..." />
       </div>
     );
   }
@@ -416,10 +417,7 @@ export const ConfigProfilesPage = () => {
   if (status === "error") {
     return (
       <div className="container">
-        <p className="text-error">Failed to load Config Profiles.</p>
-        <button onClick={loadData}>
-          <Icon name="refresh" size="sm" /> Retry
-        </button>
+        <ErrorState message="Failed to load Config Profiles." onRetry={loadData} />
       </div>
     );
   }