adds file based routing to arc.codes with enhance.dev server rendered custom elements

public/ ............... static assets
app/
├── api/ .............. api routes
├── elements/ ......... custom elements named-like-this
└── pages/ ............ html or custom elements that are routes (eg. about.html renders /about)
    ├── about.mjs
    ├── index.html
    └── notes/
        ├── $id.mjs ... url parameters are supported
        └── index.mjs

file based routing using leading $ for dynamic parameters reasoning

• $ is safe on windows and linux UNLESS its trailing in which case thats a hidden file in windows
• : is illegal in windows file paths
• * will expand in various system shells creating ambiguity
• . is meaningful in system shells (current dir) and completions with .. and/or ... creates ambiguity