Implement reactive text nodes & fix LLVM syntax for clang 20

**Reactive Text Nodes:**
- F-strings with signal dependencies now update automatically
- Added js_create_text_with_int() and js_update_text_with_int() for efficient "prefix{int}" pattern
- Text nodes stored in @reactive_text_N_node globals for updates
- Scan and track f-string dependencies during collection phase

**Binary Operations:**
- Implemented BinOp support in parser and codegen
- Maps Add → add i32, Sub → sub i32, Mult → mul i32, Div → sdiv i32, Mod → srem i32
- count = count + 1 now generates correct arithmetic instead of store i32 0

**LLVM Syntax Fixes (clang 20 compatibility):**
- Fixed getelementptr syntax: removed parentheses around type
- Before: getelementptr inbounds ([N x i8], [N x i8]* @str, ...)
- After:  getelementptr inbounds [N x i8], [N x i8]* @str, ...
- Created _emit_string_ptr() helper for consistent string pointer generation
- Fixed in: element creation, attribute setting, event binding, select instructions

**Runtime (ritz-runtime.js):**
- Added js_create_text_with_int(prefix, intValue) - creates text node with "prefix" + intValue
- Added js_update_text_with_int(node, prefix, intValue) - updates text content

**Result:**
✅ TextInput counter increments/decrements correctly
✅ Tabs example works (reactive attributes, conditionals)
✅ Both examples compile with clang 20

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

examples/runtime/ritz-runtime.js

@@ -95,6 +95,26 @@ class RitzRuntime {
         }
     }
 
+    js_create_text_with_int(prefixPtr, intValue) {
+        const prefix = this.readString(prefixPtr);
+        const text = prefix + intValue.toString();
+        const textNode = document.createTextNode(text);
+        const id = this.nextNodeId++;
+        this.nodes.set(id, textNode);
+        this._log(`createTextWithInt("${prefix}", ${intValue}) = "${text}" (id=${id})`);
+        return id;
+    }
+
+    js_update_text_with_int(nodeId, prefixPtr, intValue) {
+        const node = this.nodes.get(nodeId);
+        const prefix = this.readString(prefixPtr);
+        const text = prefix + intValue.toString();
+        if (node) {
+            node.textContent = text;
+            this._log(`updateTextWithInt(${nodeId}, "${prefix}", ${intValue}) = "${text}"`);
+        }
+    }
+
     // ===== Signal Management =====
 
     updateSignals() {
@@ -288,11 +308,13 @@ class RitzLoader {
                 env: {
                     js_create_element: (ptr) => runtime.js_create_element(ptr),
                     js_create_text: (ptr) => runtime.js_create_text(ptr),
+                    js_create_text_with_int: (p, i) => runtime.js_create_text_with_int(p, i),
                     js_append_child: (p, c) => runtime.js_append_child(p, c),
                     js_set_attribute: (e, n, v) => runtime.js_set_attribute(e, n, v),
                     js_set_root: (e) => runtime.js_set_root(e),
                     js_bind_event: (e, n, h) => runtime.js_bind_event(e, n, h),
                     js_update_text_content: (n, t) => runtime.js_update_text_content(n, t),
+                    js_update_text_with_int: (n, p, i) => runtime.js_update_text_with_int(n, p, i),
                     js_create_marker: () => runtime.js_create_marker(),
                     js_replace_at_marker: (m, o, n) => runtime.js_replace_at_marker(m, o, n),
                 }