Switch firstmate to OpenCode 2 and refresh nix-darwin pins

Point fm at the isolated oc2 wrapper, upgrade Homebrew packages on rebuild, and declare ffmpeg, docker-desktop, puremac, utm, node, and tea. Update nixpkgs, home-manager, and nix-homebrew locks. Track Pi agent config, crew-dispatch, and the Gitea PR helper that home.nix already expected.

home/.pi/agent/extensions/calm/lib/visibility.ts

@@ -0,0 +1,39 @@
+// Pi Calm - shared presentation state for the standalone Calm extension.
+//
+// Adapted from the Firstmate project's Calm implementation.
+// Copyright (c) 2026 Kun Chen. MIT License - see the LICENSE file in this directory.
+//
+// This module owns only the in-memory presentation flags. Presentation filtering
+// must never delete or alter semantic, session, or export data, so the export
+// path forces stock rendering for the duration of an /export or /share command.
+
+let active = false;
+let stockExportRendering = false;
+
+/** True while Calm presentation filtering is enabled. */
+export function calmPresentationIsActive(): boolean {
+  return active;
+}
+
+export function setCalmPresentation(next: boolean): void {
+  active = next;
+}
+
+/** True while an /export or /share render is in flight and stock output is required. */
+export function calmStockExportRenderingIsActive(): boolean {
+  return stockExportRendering;
+}
+
+export function setCalmStockExportRendering(next: boolean): void {
+  stockExportRendering = next;
+}
+
+/**
+ * True while Calm should hide the supported transcript chrome: collapsed
+ * thinking labels and the known Pi built-in tool call/result shells. Genuine
+ * user prompts, assistant text, custom tools, and every other transcript row
+ * class are never filtered by this flag.
+ */
+export function calmHidesTranscriptChrome(): boolean {
+  return active && !stockExportRendering;
+}