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* Update outdated readme info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

editor/Cargo.toml

@@ -29,12 +29,13 @@ log = { workspace = true }
 bitflags = { workspace = true }
 thiserror = { workspace = true }
 serde = { workspace = true }
+serde_bytes = { workspace = true }
 serde_json = { workspace = true }
 kurbo = { workspace = true }
 futures = { workspace = true }
 glam = { workspace = true }
 derivative = { workspace = true }
-specta = { workspace = true }
+tsify = { workspace = true }
 dyn-any = { workspace = true }
 num_enum = { workspace = true }
 usvg = { workspace = true }