Implementing app search feature (#1302)

This PR implements app search feature and addresses the issue #1182.
    
<!-- This is an auto-generated description by cubic. -->
---

## Summary by cubic
Adds a fast app search with a command-style dialog so users can find
apps by name or chat content and jump to them quickly. Implements the
search experience requested in #1182.

- New Features
- Search dialog (Ctrl+K or “Search Apps” button) with result snippets
from matching chat titles/messages.
- Searches across app names, chat titles, and message content;
case-insensitive; supports partial matches; empty query lists all apps.
  - Selecting a result navigates to the app and closes the dialog.
- New IPC endpoint search-app with Zod-validated results, debounced
React Query hook, and preload allowlist update.
- Added E2E tests for dialog open/close, shortcuts, matching behavior,
empty state, and navigation.

<!-- End of auto-generated description by cubic. -->

src/components/AppSearchDialog.tsx

@@ -0,0 +1,153 @@
+import {
+  CommandDialog,
+  CommandInput,
+  CommandList,
+  CommandEmpty,
+  CommandGroup,
+  CommandItem,
+} from "./ui/command";
+import { useState, useEffect } from "react";
+import { useSearchApps } from "@/hooks/useSearchApps";
+import type { AppSearchResult } from "@/lib/schemas";
+
+type AppSearchDialogProps = {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  onSelectApp: (appId: number) => void;
+  allApps: AppSearchResult[];
+};
+
+export function AppSearchDialog({
+  open,
+  onOpenChange,
+  onSelectApp,
+  allApps,
+}: AppSearchDialogProps) {
+  const [searchQuery, setSearchQuery] = useState<string>("");
+  function useDebouncedValue<T>(value: T, delay: number): T {
+    const [debounced, setDebounced] = useState<T>(value);
+    useEffect(() => {
+      const handle = setTimeout(() => setDebounced(value), delay);
+      return () => clearTimeout(handle);
+    }, [value, delay]);
+    return debounced;
+  }
+
+  const debouncedQuery = useDebouncedValue(searchQuery, 150);
+  const { apps: searchResults } = useSearchApps(debouncedQuery);
+
+  // Show all apps if search is empty, otherwise show search results
+  const appsToShow: AppSearchResult[] =
+    debouncedQuery.trim() === "" ? allApps : searchResults;
+
+  const commandFilter = (
+    value: string,
+    search: string,
+    keywords?: string[],
+  ): number => {
+    const q = search.trim().toLowerCase();
+    if (!q) return 1;
+    const v = (value || "").toLowerCase();
+    if (v.includes(q)) {
+      // Higher score for earlier match in title/value
+      return 100 - Math.max(0, v.indexOf(q));
+    }
+    const foundInKeywords = (keywords || []).some((k) =>
+      (k || "").toLowerCase().includes(q),
+    );
+    return foundInKeywords ? 50 : 0;
+  };
+
+  function getSnippet(
+    text: string,
+    query: string,
+    radius = 50,
+  ): {
+    before: string;
+    match: string;
+    after: string;
+    raw: string;
+  } {
+    const q = query.trim();
+    const lowerText = text.toLowerCase();
+    const lowerQuery = q.toLowerCase();
+    const idx = lowerText.indexOf(lowerQuery);
+    if (idx === -1) {
+      const raw =
+        text.length > radius * 2 ? text.slice(0, radius * 2) + "…" : text;
+      return { before: "", match: "", after: "", raw };
+    }
+    const start = Math.max(0, idx - radius);
+    const end = Math.min(text.length, idx + q.length + radius);
+    const before = (start > 0 ? "…" : "") + text.slice(start, idx);
+    const match = text.slice(idx, idx + q.length);
+    const after =
+      text.slice(idx + q.length, end) + (end < text.length ? "…" : "");
+    return { before, match, after, raw: before + match + after };
+  }
+
+  useEffect(() => {
+    const down = (e: KeyboardEvent) => {
+      if (e.key === "k" && (e.metaKey || e.ctrlKey)) {
+        e.preventDefault();
+        onOpenChange(!open);
+      }
+    };
+    document.addEventListener("keydown", down);
+    return () => document.removeEventListener("keydown", down);
+  }, [open, onOpenChange]);
+
+  return (
+    <CommandDialog
+      open={open}
+      onOpenChange={onOpenChange}
+      data-testid="app-search-dialog"
+      filter={commandFilter}
+    >
+      <CommandInput
+        placeholder="Search apps"
+        value={searchQuery}
+        onValueChange={setSearchQuery}
+        data-testid="app-search-input"
+      />
+      <CommandList data-testid="app-search-list">
+        <CommandEmpty data-testid="app-search-empty">
+          No results found.
+        </CommandEmpty>
+        <CommandGroup heading="Apps" data-testid="app-search-group">
+          {appsToShow.map((app) => {
+            const isSearch = searchQuery.trim() !== "";
+            let snippet = null;
+            if (isSearch && app.matchedChatMessage) {
+              snippet = getSnippet(app.matchedChatMessage, searchQuery);
+            } else if (isSearch && app.matchedChatTitle) {
+              snippet = getSnippet(app.matchedChatTitle, searchQuery);
+            }
+            return (
+              <CommandItem
+                key={app.id}
+                onSelect={() => onSelectApp(app.id)}
+                value={app.name + (snippet ? ` ${snippet.raw}` : "")}
+                keywords={snippet ? [snippet.raw] : []}
+                data-testid={`app-search-item-${app.id}`}
+              >
+                <div className="flex flex-col">
+                  <span>{app.name}</span>
+                  {snippet && (
+                    <span className="text-xs text-muted-foreground mt-1 line-clamp-2">
+                      {snippet.before}
+                      <mark className="bg-transparent underline decoration-2 decoration-primary">
+                        {snippet.match}
+                      </mark>
+                      {snippet.after}
+                    </span>
+                  )}
+                </div>
+              </CommandItem>
+            );
+          })}
+        </CommandGroup>
+      </CommandList>
+    </CommandDialog>
+  );
+}