refactor: migrated packages to internal utility modules and removed external dependencies

- Implemented in-house, zero-dependency utility modules in `pi-utils` covering DOM manipulation, markdown parsing, templating, browser automation helpers, and terminal buffers.
- Migrated packages across the repository to consume the new internal utilities and `omptype` schema validators instead of external dependencies.
- Removed multiple external runtime and development dependencies including Zod, Marked, LRU cache, Turndown, and Puppeteer browser packages.

packages/coding-agent/examples/custom-tools/README.md

@@ -96,7 +96,7 @@ renderResult(result, { expanded, isPartial }, theme) {
 **Use `z.enum` for discriminated string tool args:**
 
 ```typescript
-const { z } = pi.zod;
+const z = pi.zod;
 
 parameters: z.object({
 	action: z.enum(["list", "add"]),

packages/coding-agent/examples/extensions/README.md

@@ -114,7 +114,7 @@ export default function (pi: ExtensionAPI) {
 **Use `z.enum` for discriminated string tool args:**
 
 ```typescript
-const { z } = pi.zod;
+const z = pi.zod;
 
 parameters: z.object({
 	action: z.enum(["list", "add"]),

packages/coding-agent/examples/extensions/api-demo.ts

@@ -1,14 +1,13 @@
 /**
  * API Demo Extension
  *
- * Demonstrates using ExtensionAPI's logger, injected `pi.zod`, and pi module access.
- * These features are now exposed directly on the ExtensionAPI, matching
- * the CustomToolAPI interface.
+ * Demonstrates using ExtensionAPI's logger, injected schema builder, and pi
+ * module access.
  */
 import type { ExtensionAPI } from "@oh-my-pi/pi-coding-agent";
 
 export default function (pi: ExtensionAPI) {
-	const { z } = pi.zod;
+	const z = pi.zod;
 
 	// Access the logger for debugging
 	pi.logger.debug("API demo extension loaded");
@@ -16,7 +15,7 @@ export default function (pi: ExtensionAPI) {
 	pi.registerTool({
 		name: "api_demo",
 		label: "API Demo",
-		description: "Demonstrates ExtensionAPI capabilities: logger, zod, and pi module access",
+		description: "Demonstrates ExtensionAPI capabilities: logger, schema validation, and pi module access",
 		parameters: z.object({
 			message: z.string().describe("Test message"),
 			logLevel: z.enum(["error", "warn", "debug"]).default("debug").describe("Log level to use"),
@@ -48,7 +47,7 @@ export default function (pi: ExtensionAPI) {
 							``,
 							`Features demonstrated:`,
 							`1. ✓ Logger access via pi.logger`,
-							`2. ✓ Zod access via pi.zod`,
+							`2. ✓ Schema builder access via pi.arktype`,
 							`3. ✓ Pi module access via pi.pi`,
 							``,
 							`Context:`,

packages/coding-agent/examples/extensions/chalk-logger.ts

@@ -3,7 +3,7 @@
  * Tests that jiti can resolve npm modules correctly.
  */
 import type { ExtensionAPI } from "@oh-my-pi/pi-coding-agent";
-import chalk from "chalk";
+import chalk from "@oh-my-pi/pi-utils/chalk";
 
 export default function (pi: ExtensionAPI) {
 	// Log with colors using chalk

packages/coding-agent/examples/extensions/hello.ts

@@ -1,12 +1,12 @@
 /**
  * Hello Tool - Minimal custom tool example
  *
- * Demonstrates using ExtensionAPI's logger, injected `pi.zod`, and pi module access.
+ * Demonstrates using ExtensionAPI's logger and injected schema builder.
  */
 import type { ExtensionAPI } from "@oh-my-pi/pi-coding-agent";
 
 export default function (pi: ExtensionAPI) {
-	const { z } = pi.zod;
+	const z = pi.zod;
 
 	pi.registerTool({
 		name: "hello",

packages/coding-agent/examples/extensions/reload-runtime.ts

@@ -8,7 +8,7 @@
 import type { ExtensionAPI } from "@oh-my-pi/pi-coding-agent";
 
 export default function (pi: ExtensionAPI) {
-	const { z } = pi.zod;
+	const z = pi.zod;
 
 	// Command entrypoint for reload.
 	// Treat reload as terminal for this handler.

packages/coding-agent/examples/extensions/with-deps/index.ts

@@ -8,7 +8,7 @@ import type { ExtensionAPI } from "@oh-my-pi/pi-coding-agent";
 import ms from "ms";
 
 export default function (pi: ExtensionAPI) {
-	const { z } = pi.zod;
+	const z = pi.zod;
 
 	// Register a tool that uses ms
 	pi.registerTool({

packages/coding-agent/examples/sdk/06-extensions.ts

@@ -41,7 +41,7 @@ console.log();
 import type { ExtensionAPI } from "@oh-my-pi/pi-coding-agent";
 
 export default function (pi: ExtensionAPI) {
-	const { z } = pi.zod;
+	const z = pi.zod;
 
 	pi.on("agent_start", async () => {
 		console.log("[Extension] Agent starting");