feat: remove legacy OpenCode runtime

Cut product flows over to Coding/Pi and retain only the migration-owned v1 boundary. Promote supported native optional packages because electron-builder omitted pnpm transitive optional closure from the packaged ASAR.

tests/unit/coding-chat-panel.test.tsx

@@ -104,6 +104,11 @@ const projectApi = vi.hoisted(() => ({
   conversations: vi.fn(),
   create: vi.fn(),
   patch: vi.fn(),
+  open: vi.fn(),
+  createProject: vi.fn(),
+  setActive: vi.fn(),
+  removeProject: vi.fn(),
+  acknowledgeNotice: vi.fn(),
 }));
 const conversationApi = vi.hoisted(() => ({
   snapshot: vi.fn(),
@@ -126,6 +131,11 @@ vi.mock('@/lib/coding-projects', () => ({
   listCodingProjectConversations: projectApi.conversations,
   createCodingProjectConversation: projectApi.create,
   patchCodingProjectConversation: projectApi.patch,
+  openCodingProject: projectApi.open,
+  createCodingProject: projectApi.createProject,
+  setActiveCodingProject: projectApi.setActive,
+  removeCodingProject: projectApi.removeProject,
+  acknowledgeLegacyCodingConversationNotice: projectApi.acknowledgeNotice,
 }));
 
 vi.mock('@/lib/coding-conversations', () => ({