fix(engine): register grep/find/ls alongside read/bash/edit/write for coding sessions

pi-coding-agent 0.70's createCodingTools preset only includes read/bash/edit/write,
but pi-claude-cli's tool-mapping translates Claude's Glob→find and Grep→grep.
Triage sessions running through Claude CLI hit "Tool find not found" the moment
the model called Glob and looped on the error.

Compose the built-in set explicitly so every tool referenced by tool-mapping.ts
is registered. Read-only sessions also gain ls (was silently dropped earlier
when readonly was redefined upstream).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/engine/src/__tests__/pi.test.ts

@@ -35,6 +35,13 @@ vi.mock("@mariozechner/pi-coding-agent", () => ({
   })),
   createCodingTools: vi.fn(() => []),
   createReadOnlyTools: vi.fn(() => []),
+  createReadTool: vi.fn(() => ({ name: "read" })),
+  createBashTool: vi.fn(() => ({ name: "bash" })),
+  createEditTool: vi.fn(() => ({ name: "edit" })),
+  createWriteTool: vi.fn(() => ({ name: "write" })),
+  createGrepTool: vi.fn(() => ({ name: "grep" })),
+  createFindTool: vi.fn(() => ({ name: "find" })),
+  createLsTool: vi.fn(() => ({ name: "ls" })),
   createExtensionRuntime: vi.fn(),
   DefaultResourceLoader: vi.fn().mockImplementation(() => ({
     reload: vi.fn().mockResolvedValue(undefined),