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/server/src/routes/sessions.ts

@@ -33,7 +33,8 @@ const WorkspacePaneZ = z.object({
   kind: z.enum([
     'chat',
     'terminal',
-    'agent',
+    'coder',
+    'agent', // legacy alias — normalized to coder on write
     'empty',
     'settings',
     'markdown_artifact',
@@ -307,9 +308,12 @@ export function registerSessionRoutes(
         reply.code(400);
         return { error: 'invalid body', details: parsed.error.flatten() };
       }
+      const workspacePanes = parsed.data.workspace_panes.map((pane) =>
+        pane.kind === 'agent' ? { ...pane, kind: 'coder' as const } : pane,
+      );
       const rows = await sql<Session[]>`
         UPDATE sessions
-        SET workspace_panes = ${sql.json(parsed.data.workspace_panes as never)},
+        SET workspace_panes = ${sql.json(workspacePanes as never)},
             updated_at = clock_timestamp()
         WHERE id = ${req.params.id}
         RETURNING id, project_id, name, model, system_prompt, status, created_at, updated_at,