feat(tools): add run_shell, edit_file, write_file + read_file directory listing

Four standard-tier tool extensions (one tool per extension, zero ABI change):
- tool-read-file: read_file now lists directory contents (sorted, /-suffixed subdirs)
- tool-shell: run_shell (foreground, streamed, cancellable, cwd, timeout + output cap)
- tool-edit-file: edit_file (oldString/newString/replaceAll; errors on absent/non-unique)
- tool-write-file: write_file (explicit overwrite flag)
Registered in host-bin CORE_EXTENSIONS. Live boot clean (shell capability accepted).
686 vitest + 89 bun = 775 tests; tsc -b EXIT 0; biome clean.

1 files changed, 19 insertions, 0 deletions

diff --git a/packages/tool-shell/src/extension.ts b/packages/tool-shell/src/extension.ts
new file mode 100644
index 0000000..1a89de0
--- /dev/null
+++ b/packages/tool-shell/src/extension.ts
@@ -0,0 +1,19 @@
+import type { Extension } from "@dispatch/kernel";
+import { createRunShellTool } from "./shell.js";
+import { realSpawn } from "./spawn.js";
+
+export const extension: Extension = {
+	manifest: {
+		id: "tool-shell",
+		name: "Shell Tool",
+		version: "0.0.0",
+		apiVersion: "^0.1.0",
+		trust: "bundled",
+		activation: "eager",
+		capabilities: { shell: true },
+		contributes: { tools: ["run_shell"] },
+	},
+	activate(host) {
+		host.defineTool(createRunShellTool({ workdir: process.cwd(), spawn: realSpawn }));
+	},
+};