[LLV] Refactor JS distribution

[FranekKubis]

Summary

Refactor JS distribution: ship local_live_view.js pre-bundled inside the hex package instead of building it user-side via npm. End users now import via package name (import "local_live_view") instead of relative vendor path, and mix llv.build drops the npm/node steps entirely.

Changes

Library side:

• New local-live-view/package.json with main: "priv/static/local_live_view.js" for esbuild's NODE_PATH resolution (NODE_PATH points to "deps" directory).
• priv/static/{local_live_view.js, iframe.mjs, AtomVM.mjs, AtomVM.wasm} committed (pre-bundled at release time via assets/bundle.mjs).
• mix llv.build simplified: copies runtime files from deps/local_live_view/priv/static/ to user's priv/static/assets/js/, then builds WASM. No npm, no node.
• llv.install template injects import { LLVEngine } from "local_live_view" (was from "../vendor/local_live_view.js").

Examples (local-lv-{compare,forms,thermostat,pong,burrito}):

• Migrated to standard Phoenix esbuild pipeline (away from custom build.mjs + node watcher).
• (!) Each assets/package.json declares "local_live_view": "workspace:*" so pnpm symlinks LLV into node_modules/ (path deps don't get deps/<name>/ from Mix — workspace fills the gap in monorepo).
• bundlePaths fixed to match out_dir (/assets/js/wasm/bundle.avm).
• pnpm-workspace.yaml includes local-live-view and missing example entries.