Fix dev environment configurations with devcontainer, vscode, and cargo-about (#4372)

Some minor fixes to issues I ran into using devcontainer on this project
with vscode.
 
- Add `esbenp.prettier-vscode` to the recommended extensions list as
it's already used in `.vscode/settings.json`
- Install `wasm32-unknown-unknown` Rust target in devcontainer
- Add cargo-binstall and pin cargo-about version in devcontainer
- Remove `no-clearly-defined = true` from `about.toml`:
  - cargo-about 0.9.1 fails to run if `no-clearly-defined` is present
- cargo-about 0.8.0 already [removed
support](https://github.com/EmbarkStudios/cargo-about/blob/main/CHANGELOG.md#080---2025-09-05)
for clearlydefined.io, so the argument is a no-op

.vscode/extensions.json

@@ -6,6 +6,7 @@
 		"tamasfe.even-better-toml",
 		// Web
 		"dbaeumer.vscode-eslint",
+		"esbenp.prettier-vscode",
 		"svelte.svelte-vscode",
 		"vitaliymaz.vscode-svg-previewer",
 		// Code quality