feat: add stdlib and browser examples

- stdlib/html.lux: Type-safe HTML construction
- stdlib/browser.lux: Browser utilities
- examples/web/: Counter app with DOM manipulation
- examples/counter.lux: Simple counter example

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

examples/web/counter.js

@@ -0,0 +1,144 @@
+// Lux Runtime
+const Lux = {
+    Some: (value) => ({ tag: "Some", value }),
+    None: () => ({ tag: "None" }),
+    
+    Ok: (value) => ({ tag: "Ok", value }),
+    Err: (error) => ({ tag: "Err", error }),
+    
+    Cons: (head, tail) => [head, ...tail],
+    Nil: () => [],
+    
+    defaultHandlers: {
+        Console: {
+            print: (msg) => console.log(msg),
+            readLine: () => {
+                if (typeof require !== 'undefined') {
+                    const readline = require('readline');
+                    const rl = readline.createInterface({ input: process.stdin, output: process.stdout });
+                    return new Promise(resolve => rl.question('', answer => { rl.close(); resolve(answer); }));
+                }
+                return prompt('') || '';
+            },
+            readInt: () => parseInt(Lux.defaultHandlers.Console.readLine(), 10)
+        },
+        Random: {
+            int: (min, max) => Math.floor(Math.random() * (max - min + 1)) + min,
+            bool: () => Math.random() < 0.5,
+            float: () => Math.random()
+        },
+        Time: {
+            now: () => Date.now(),
+            sleep: (ms) => new Promise(resolve => setTimeout(resolve, ms))
+        },
+        Http: {
+            get: async (url) => {
+                try {
+                    const response = await fetch(url);
+                    const body = await response.text();
+                    const headers = [];
+                    response.headers.forEach((v, k) => headers.push([k, v]));
+                    return Lux.Ok({ status: response.status, body, headers });
+                } catch (e) {
+                    return Lux.Err(e.message);
+                }
+            },
+            post: async (url, body) => {
+                try {
+                    const response = await fetch(url, { method: 'POST', body });
+                    const respBody = await response.text();
+                    const headers = [];
+                    response.headers.forEach((v, k) => headers.push([k, v]));
+                    return Lux.Ok({ status: response.status, body: respBody, headers });
+                } catch (e) {
+                    return Lux.Err(e.message);
+                }
+            },
+            postJson: async (url, json) => {
+                try {
+                    const response = await fetch(url, {
+                        method: 'POST',
+                        headers: { 'Content-Type': 'application/json' },
+                        body: JSON.stringify(json)
+                    });
+                    const body = await response.text();
+                    const headers = [];
+                    response.headers.forEach((v, k) => headers.push([k, v]));
+                    return Lux.Ok({ status: response.status, body, headers });
+                } catch (e) {
+                    return Lux.Err(e.message);
+                }
+            }
+        }
+    }
+};
+
+// Model constructors
+function Counter_lux(field0) { return { tag: "Counter", field0: field0 }; }
+
+// Msg constructors
+const Increment_lux = { tag: "Increment" };
+const Decrement_lux = { tag: "Decrement" };
+const Reset_lux = { tag: "Reset" };
+
+function getCount_lux(m) {
+    const _match_0 = m;
+    let _result_1;
+    if (_match_0.tag === "Counter") {
+        const n = _match_0.field0;
+        _result_1 = n;
+    } else {
+        throw new Error('Non-exhaustive match on ' + JSON.stringify(_match_0));
+    }
+    return _result_1;
+}
+
+function init_lux() {
+    return Counter_lux(0);
+}
+
+function update_lux(model, msg) {
+    const _match_2 = msg;
+    let _result_3;
+    if (_match_2.tag === "Increment") {
+        _result_3 = Counter_lux((getCount_lux(model) + 1));
+    } else if (_match_2.tag === "Decrement") {
+        _result_3 = Counter_lux((getCount_lux(model) - 1));
+    } else if (_match_2.tag === "Reset") {
+        _result_3 = Counter_lux(0);
+    } else {
+        throw new Error('Non-exhaustive match on ' + JSON.stringify(_match_2));
+    }
+    return _result_3;
+}
+
+function view_lux(model) {
+    const count_4 = getCount_lux(model);
+    return (((((((((("<div class=\"counter\">" + "<h1>Lux Counter</h1>") + "<div class=\"display\">") + String(count_4)) + "</div>") + "<div class=\"buttons\">") + "<button onclick=\"dispatch('Decrement')\">-</button>") + "<button onclick=\"dispatch('Reset')\">Reset</button>") + "<button onclick=\"dispatch('Increment')\">+</button>") + "</div>") + "</div>");
+}
+
+function luxInit_lux() {
+    return init_lux();
+}
+
+function luxUpdate_lux(model, msgName) {
+    const _match_5 = msgName;
+    let _result_6;
+    if (_match_5 === "Increment") {
+        _result_6 = update_lux(model, Increment_lux);
+    } else if (_match_5 === "Decrement") {
+        _result_6 = update_lux(model, Decrement_lux);
+    } else if (_match_5 === "Reset") {
+        _result_6 = update_lux(model, Reset_lux);
+    } else if (true) {
+        _result_6 = model;
+    } else {
+        throw new Error('Non-exhaustive match on ' + JSON.stringify(_match_5));
+    }
+    return _result_6;
+}
+
+function luxView_lux(model) {
+    return view_lux(model);
+}
+