Rename Agent mode to Build with MCP in UI (#1966)

<!-- CURSOR_SUMMARY -->
> [!NOTE]
> Rename the “Agent” chat mode to “Build with MCP” and update its label
and description in `src/components/ChatModeSelector.tsx`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
a5ad57fa2492941186c0cdba9ea9d6340817ea6b. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->



<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Renamed the “Agent” chat mode to “Build with MCP” and added shared
module support for Supabase Edge Functions, including automatic
redeploys when shared code changes.

- **New Features**
- Updated UI: “Agent” → “Build (MCP)” in mode name and “Build with MCP
(experimental)” in selector.
- Detect changes in supabase/functions/_shared and redeploy all
functions accordingly.
- Deploy functions with their full directory plus shared files; add an
import_map to resolve “_shared/” imports.
  - Cache shared files by signature to avoid redundant reads.
  - Added tests for path helpers and signature building.

- **Refactors**
- deploySupabaseFunctions now accepts appPath and functionPath, and
uploads multiple files instead of a single content string.
- Updated app and response handlers to use the new deploy flow, skip
per-function redeploys when shared modules change, and avoid treating
_shared as a function.
- Added isSharedServerModule and refined isServerFunction to exclude
_shared.

<sup>Written for commit a5ad57fa2492941186c0cdba9ea9d6340817ea6b.
Summary will update automatically on new commits.</sup>

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

src/components/ChatModeSelector.tsx

@@ -31,7 +31,7 @@ export function ChatModeSelector() {
       case "ask":
         return "Ask";
       case "agent":
-        return "Agent";
+        return "Build (MCP)";
       default:
         return "Build";
     }
@@ -83,9 +83,9 @@ export function ChatModeSelector() {
         </SelectItem>
         <SelectItem value="agent">
           <div className="flex flex-col items-start">
-            <span className="font-medium">Agent (experimental)</span>
+            <span className="font-medium">Build with MCP (experimental)</span>
             <span className="text-xs text-muted-foreground">
-              Agent can use tools (MCP) and generate code
+              Like Build, but can use tools (MCP) to generate code
             </span>
           </div>
         </SelectItem>