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/git-history.tsx

@@ -2,6 +2,7 @@ import { useCallback, useEffect, useState } from "react";
 import { useNavigate, useParams } from "react-router-dom";
 
 import { getCommitDetail, getRepositoryHistory, type CommitDetail, type CommitHistoryEntry, type CommitHistoryResponse } from "../api/git_repositories";
+import { EmptyState, ErrorState, LoadingState } from "../components/data-states";
 import { Icon } from "../components/icon";
 import { useAsyncData } from "../hooks/use-async-data";
 
@@ -54,7 +55,7 @@ export const GitHistoryPage = () => {
   if (status === "loading") {
     return (
       <section className="stack">
-        <p className="muted">Loading commit history...</p>
+        <LoadingState message="Loading commit history..." />
       </section>
     );
   }
@@ -62,11 +63,7 @@ export const GitHistoryPage = () => {
   if (status === "error") {
     return (
       <section className="stack">
-        <p>Failed to load commit history</p>
-        <button className="secondary-button" onClick={() => reload()} type="button">
-          <Icon name="refresh" size="sm" />
-          Retry
-        </button>
+        <ErrorState message="Failed to load commit history" onRetry={reload} />
       </section>
     );
   }