Draft: Polaris frame, Modals, and more!

[Kashuab]

Disclaimer: This is a draft PR, still some more work to do :) Please feel free to take a look though!

Related issues #2, #7, #5, #4, #3

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Hey! I finally got some time to sink my teeth into this. 😄

This PR has a lot of changes, and will probably get more as I continue to flesh out modals. My goals were:

• Get the "Shopify admin" wrapper to look more like Shopify
• Separate some concerns, "server", "app bridge" and "admin frame" should be separate things (in my opinion!)
• Create a more scalable, type-safe mechanism for postMessage comms between the admin frame and client app bridge
• Work out of box with Shopify app remix template (and I guess React Router now? 😛)

In doing so, I've introduced a plethora of changes:

• Created new directory containing a Vite SPA for the admin frame
• Polaris web components worked OOB after I added their script :)
• Created new directory containing the client app bridge source (now in TypeScript + build scripts!)
• Fixed a bug where the default value for --shop would override the shop I have set in config
• Accept a user ID which is encoded into session tokens (TODO: needs CLI arg)
• Add session token to initial iframe src via id_token param, my Remix app needed this
• Implemented a system where you can define "features" as Zustand stores (see Modal feature)
• Started work on modals (Works actually!)
• Added boilerplate features on window.shopify definition, give those a place to live for future iteration
• Added docs for Remix integration

PLEASE ask me all the questions and give any feedback (maybe aside from code review, it's unfinished!) Let me know if this is in-line with your vision or if there is some contribution etiquette I'm missing!

So much more TODO, including adding more info to this description. It's Saturday evening and I'm craving some brew 🍺

Remaining tasks in this PR:

• Improve wrapper UI to match Shopify admin (currently is just a Polaris web components proof of concept)
• Finish up modals feature (ensure MutationObserver works properly, modal content should be dynamic, unmounting should invoke cleanup, etc.)
• invokeFeature is fine for unidirectional/opaque flow (app iframe -> parent) but what if the parent wants to return data? 🤔
• Document "features" for future contributors. We'll need some help reverse engineering app-bridge, let alone keeping it up-to-date 😅
• Ensure no/minimal breaking changes (don't want to break your stuff!)
• Clean up code
• Tests...? Too early to invest in? 🤷

[Kashuab]

I wish I could just use <Frame /> from Polaris React 😭

[Kashuab]

I found that this print ended up being inaccurate when my config file was applied

[Kashuab]

There's probably a better way, but this default was overriding my config

[Kashuab]

Now that I think about it, a better way to handle modal lifecycle would be to implement web components for them :P

[Zn4rK]

Is there any chance we'll get this in? This is like the missing link in Shopify App Development :)