Add Svelte docs site and WASM playground

doc/manual/souce/development.md

@@ -20,6 +20,50 @@ cargo test -p decodal-core --features regex
 cargo run -q -p decodal --features regex -- examples/regex/main.dcdl
 ```
 
+## Web site and playground
+
+The Svelte documentation site and browser playground are kept in:
+
+```text
+site/decodal-site/
+```
+
+The site imports Markdown files from `doc/manual/souce/` and renders them as mdBook-style pages.
+The playground loads `decodal-wasm` and evaluates DCDL entirely in the browser.
+
+Important files:
+
+```text
+site/decodal-site/src/App.svelte
+site/decodal-site/src/Playground.svelte
+site/decodal-site/src/lib/docs.js
+crates/decodal-wasm/src/lib.rs
+```
+
+Build the WebAssembly package before building the site:
+
+```sh
+cd site/decodal-site
+npm install
+npm run build:wasm
+npm run build
+```
+
+`npm run build:wasm` writes generated files into:
+
+```text
+site/decodal-site/src/wasm/
+```
+
+These generated files are committed so the site can be built without requiring every consumer to regenerate the wasm package first.
+
+To run the site locally:
+
+```sh
+cd site/decodal-site
+npm run dev
+```
+
 ## Tree-sitter grammar
 
 The Tree-sitter grammar is kept in:
@@ -73,7 +117,7 @@ When the Decodal syntax changes:
 
 ## Development shell
 
-The Nix development shell includes Rust tooling, Node.js, and Tree-sitter CLI tooling.
+The Nix development shell includes Rust tooling, Node.js, Tree-sitter CLI tooling, and wasm-pack tooling.
 
 ```sh
 nix develop
@@ -87,5 +131,7 @@ The shell provides:
 - `clippy`
 - `node`
 - `npm`
+- `wasm-pack`
+- `lld`
 - `tree-sitter`
 - `nixfmt`