Refactor the TypeScript data flow for full type safety and auto-generation of Rust types (#3865)

* Migrate Specta to Tsify to auto-generate messages.ts, working except colors and widgets

* Adopt the generated FillColor/Color/GradientStops

* Fix widget typing

* Separate WidgetGroup enum variants into wrapper structs

* Small rename

* Simplify widgets further

* Clean up message type references

* Switch type imports to the auto-generated file

* Remove lowercase serde rename

* Fix FillChoice deserialization

* Fix small regression from #3837

* Improve type safety

* Make WidgetSpan type-safe

* More cleanup and type safety

* More type safety

* More type safety

* Get the rest to type-check without errors; improve widget builder macro to have optional icons; improve Svelte 5 configs

* Cargo fmt

* Fix imports

* Update outdated readme info

* Fix lint command rename references

* Fix typos

* One more typos fix

* Remove unnecessary dep: prefix from the edited Cargo.toml files

* Remove excess parts from Cargo.toml

* Fix compiling on desktop

* Revert "Remove excess parts from Cargo.toml"

This reverts commit 6b711117b3a5d5d8a3ee20f36a43bc74930b7c82.

* Update dev docs with simpler, more accurate instructions

Cargo.toml

@@ -98,6 +98,7 @@ rustc-hash = "2.0"
 bytemuck = { version = "1.13", features = ["derive", "min_const_generics"] }
 serde = { version = "1.0", features = ["derive", "rc"] }
 serde_json = "1.0"
+serde_bytes = "0.11"
 serde-wasm-bindgen = "0.6"
 reqwest = { version = "0.13", features = ["blocking", "json"] }
 futures = "0.3"
@@ -176,11 +177,7 @@ fern = { version = "0.7", features = ["colored"] }
 num_enum = { version = "0.7", default-features = false }
 num-derive = "0.4"
 num-traits = { version = "0.2", default-features = false, features = ["libm"] }
-specta = { version = "2.0.0-rc.22", features = [
-	"glam",
-	"derive",
-	# "typescript",
-] }
+tsify = { version = "0.5", default-features = false, features = ["js"] }
 syn = { version = "2.0", default-features = false, features = [
 	"full",
 	"derive",
@@ -230,7 +227,6 @@ graphite-proc-macros = { opt-level = 1 }
 image = { opt-level = 2 }
 rustc-hash = { opt-level = 3 }
 serde_derive = { opt-level = 1 }
-specta-macros = { opt-level = 1 }
 syn = { opt-level = 1 }
 node-macro = { opt-level = 2 }