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/scripts/bundle-dist.ts

@@ -30,17 +30,7 @@ const ALWAYS_EXTERNAL = [
 // import would load the unpatched npm package in users' installs (currently
 // @ark/schema is patched, so it — and arktype, which pulls @ark/schema — stay
 // bundled).
-const RUNTIME_EXTERNAL = [
-	"puppeteer-core",
-	"@puppeteer/browsers",
-	"@babel/parser",
-	"@xterm/headless",
-	"turndown",
-	"turndown-plugin-gfm",
-	"@mozilla/readability",
-	"linkedom",
-	"@agentclientprotocol/sdk",
-];
+const RUNTIME_EXTERNAL = ["puppeteer-core", "@babel/parser"];
 
 async function runCommand(command: string[]): Promise<void> {
 	const proc = Bun.spawn(command, {