v2.2-paseo-providers: Paseo provider stack + v2.2.1 pane-scoped chat fixes

Ship Paseo-equivalent provider snapshot, AgentComposerBar, ACP dispatch
rewrite with streaming/persist, permission prompts, and agent commands.
Follow-up: pane-scoped chat resolution, CoderMessageList tool timeline,
WS user-delta replace, and inference orphan tool_call stripping.
Archive openspec v2-2; update CHANGELOG and CURRENT.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/coder/src/services/acp-spawn.ts

@@ -0,0 +1,29 @@
+/**
+ * Resolve ACP spawn argv per provider (host-probe verified 2026-05-25).
+ */
+export function resolveAcpSpawnArgs(agent: string): string[] | null {
+  switch (agent) {
+    case 'opencode':
+    case 'goose':
+      return ['acp'];
+    case 'cursor':
+      return ['acp'];
+    case 'copilot':
+      return ['--acp'];
+    case 'qwen':
+      return ['--acp'];
+    default:
+      return null;
+  }
+}
+
+export function resolveAcpProbeBinaries(agent: string): string[] {
+  switch (agent) {
+    case 'cursor':
+      return ['cursor-agent', 'agent'];
+    case 'copilot':
+      return ['copilot'];
+    default:
+      return [agent];
+  }
+}