feat(prime-agent): filterable project picker + a visible active-project indicator

Two gaps the pi switcher had already closed.

**The indicator was invisible.** `ctx.ui.setStatus` was the wrong channel:
prime-agent stores extension statuses (`FooterDataProvider.setExtensionStatus`)
but nothing ever reads them back — there is no `getExtensionStatuses()` call
site anywhere in the app, so the value was recorded and never rendered. pi's
`footer.js` does render them, which is why the same code showed a status line
there and nothing here. The active project is now published as a *widget*
(`extensionWidgetsBelow` → `renderWidgets()`), which prime-agent does render.
`setStatus` is still called so pi keeps its footer entry.

**No search.** With 356 projects the picker was a wall of
`smoke-mcptoken-*`. Above 20 projects it now asks for a filter first;
space-separated terms must all match, case-insensitively, against name or
description, so `home auto` finds `homeautomation`. Active project sorts
first, then alphabetical.

Deliberately no client-side truncation here, unlike the pi picker: pi's
`ExtensionSelectorComponent.updateList()` renders every option, so a long list
fills the screen and has to be capped. prime-agent's selector windows the list
itself and shows a true `(20/356)` counter — capping would replace an accurate
total with a misleading one.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017BMXdb2qZbPSh8Q7XpTyjB

src/cli/tests/commands/prime-agent.test.ts

@@ -528,6 +528,38 @@ describe('config prime-agent', () => {
     expect(ext).not.toContain("'success'");
   });
 
+  it('the installed switcher shows the active project via a widget, not just setStatus', async () => {
+    const settingsPath = join(tmpDir, 'settings.json');
+    const cmd = createConfigCommand(
+      { configDeps: { configDir: tmpDir }, log },
+      { client, credentialsDeps: { configDir: tmpDir }, log },
+    );
+    await cmd.parseAsync(['prime-agent', '--project', 'ha', '-o', settingsPath, '--skip-skills', '--token', 'mcpctl_pat_x'], { from: 'user' });
+
+    const ext = readFileSync(join(tmpDir, 'extensions', 'mcpctl-switch.ts'), 'utf-8');
+    // prime-agent stores extension statuses but never renders them, so a
+    // setStatus-only indicator is invisible there. Widgets are rendered.
+    expect(ext).toContain('ctx.ui.setWidget(STATUS_KEY');
+    expect(ext).toContain("placement: 'belowEditor'");
+    // Still set the status: pi's footer does render it.
+    expect(ext).toContain('ctx.ui.setStatus(STATUS_KEY');
+  });
+
+  it('the installed switcher filters the project list before showing it', async () => {
+    const settingsPath = join(tmpDir, 'settings.json');
+    const cmd = createConfigCommand(
+      { configDeps: { configDir: tmpDir }, log },
+      { client, credentialsDeps: { configDir: tmpDir }, log },
+    );
+    await cmd.parseAsync(['prime-agent', '--project', 'ha', '-o', settingsPath, '--skip-skills', '--token', 'mcpctl_pat_x'], { from: 'user' });
+
+    const ext = readFileSync(join(tmpDir, 'extensions', 'mcpctl-switch.ts'), 'utf-8');
+    // Hundreds of projects in a plain arrow-key list is unusable.
+    expect(ext).toContain('export function filterProjects');
+    expect(ext).toContain('ctx.ui.input(');
+    expect(ext).toContain('FILTER_THRESHOLD');
+  });
+
   it('the installed switcher extension passes --skip-marker', async () => {
     const settingsPath = join(tmpDir, 'settings.json');
     const cmd = createConfigCommand(