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/loop/run.ts

@@ -18,9 +18,9 @@ export interface LoopRunRow {
 }
 
 export interface LoopRunOptions extends CommandOptions {
-  provider?: "claude" | "codex" | "opencode";
+  provider?: string;
   model?: string;
-  verifyProvider?: "claude" | "codex" | "opencode";
+  verifyProvider?: string;
   verifyModel?: string;
   verify?: string;
   verifyCheck?: string[];

packages/cli/src/commands/loop/types.ts

@@ -45,11 +45,11 @@ export interface LoopRecord {
   name: string | null;
   prompt: string;
   cwd: string;
-  provider: "claude" | "codex" | "opencode";
+  provider: string;
   model: string | null;
-  workerProvider: "claude" | "codex" | "opencode" | null;
+  workerProvider: string | null;
   workerModel: string | null;
-  verifierProvider: "claude" | "codex" | "opencode" | null;
+  verifierProvider: string | null;
   verifierModel: string | null;
   verifyPrompt: string | null;
   verifyChecks: string[];
@@ -122,11 +122,11 @@ export interface LoopStopPayload {
 export interface LoopRunInput {
   prompt: string;
   cwd: string;
-  provider?: "claude" | "codex" | "opencode";
+  provider?: string;
   model?: string;
-  workerProvider?: "claude" | "codex" | "opencode";
+  workerProvider?: string;
   workerModel?: string;
-  verifierProvider?: "claude" | "codex" | "opencode";
+  verifierProvider?: string;
   verifierModel?: string;
   verifyPrompt?: string;
   verifyChecks?: string[];