feat: ACP base provider, Copilot integration, eliminate hardcoded provider unions (#170)

* feat(server): add ACP base provider with Claude ACP integration

Implement a generic Agent Client Protocol (ACP) base provider that any
ACP-compatible agent can extend with minimal code. Includes a concrete
Claude ACP implementation via @agentclientprotocol/claude-agent-acp
with full parity to the existing Claude Code provider.

The base handles subprocess lifecycle, streaming translation, permission
bridging, terminal/fs callbacks, listModels, loadSession/resume, and
mode/model management. The concrete class only specifies the command,
modes, and availability check.

* fix: update lockfile signatures and Nix hash

* feat: add Copilot ACP provider, eliminate hardcoded provider unions, fix ACP streaming bugs

Add Copilot as an ACP provider (copilot --acp), with real modes and models
discovered from the ACP server. Fix two ACP base bugs: duplicate assistant
text (emit deltas not cumulative) and idle→running→stuck (fire-and-return
startTurn). Replace all hardcoded provider string unions with string/manifest-
derived values so adding a provider only requires: impl class, manifest entry,
registry factory, icon, and E2E config. Add provider docs and Copilot icon.

* fix: update lockfile signatures and Nix hash

* feat(app): add OpenCode provider icon

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

packages/cli/src/commands/provider/ls.ts

@@ -1,5 +1,6 @@
 import type { Command } from "commander";
 import type { CommandOptions, ListResult, OutputSchema } from "../../output/index.js";
+import { AGENT_PROVIDER_DEFINITIONS } from "@getpaseo/server";
 
 /** Provider list item for display */
 export interface ProviderListItem {
@@ -9,27 +10,13 @@ export interface ProviderListItem {
   modes: string;
 }
 
-/** Static provider data - providers are built-in and don't require daemon */
-const PROVIDERS: ProviderListItem[] = [
-  {
-    provider: "claude",
-    status: "available",
-    defaultMode: "default",
-    modes: "plan, default, bypass",
-  },
-  {
-    provider: "codex",
-    status: "available",
-    defaultMode: "auto",
-    modes: "read-only, auto, full-access",
-  },
-  {
-    provider: "opencode",
-    status: "available",
-    defaultMode: "default",
-    modes: "plan, default, bypass",
-  },
-];
+/** Derive provider list from the manifest — single source of truth */
+const PROVIDERS: ProviderListItem[] = AGENT_PROVIDER_DEFINITIONS.map((def) => ({
+  provider: def.id,
+  status: "available",
+  defaultMode: def.defaultModeId ?? "default",
+  modes: def.modes.map((m) => m.label).join(", "),
+}));
 
 /** Schema for provider ls output */
 export const providerLsSchema: OutputSchema<ProviderListItem> = {