feat: Initialize compiler GUI project

Sets up the basic structure for the compiler GUI application using
eframe.
This includes the main application loop, a default UI layout with a
source code editor and an output log panel, and the foundational AST
(Abstract Syntax Tree) definitions for types, nodes, and an evaluation
mechanism.

src/main.rs

@@ -0,0 +1,115 @@
+use eframe::egui;
+
+pub mod ast;
+
+fn main() -> eframe::Result {
+    let options = eframe::NativeOptions {
+        viewport: egui::ViewportBuilder::default().with_inner_size([800.0, 600.0]),
+        ..Default::default()
+    };
+    eframe::run_native(
+        "Compiler GUI",
+        options,
+        Box::new(|_cc| Ok(Box::new(CompilerApp::default()))),
+    )
+}
+
+struct CompilerApp {
+    source_code: String,
+    output_log: String,
+}
+
+impl Default for CompilerApp {
+    fn default() -> Self {
+        Self {
+            source_code: String::new(),
+            output_log: String::from("Ready to compile..."),
+        }
+    }
+}
+
+impl eframe::App for CompilerApp {
+    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
+        // Bottom Panel: Output Log & Controls (Resizable)
+        egui::TopBottomPanel::bottom("bottom_panel")
+            .resizable(true)
+            .min_height(150.0)
+            .default_height(250.0)
+            .show(ctx, |ui| {
+                ui.add_space(5.0);
+
+                // Compile Button (at the top of the bottom panel)
+                if ui.button("Compile").clicked() {
+                    use crate::ast::*;
+                    use std::sync::Arc;
+
+                    // 1. Create shared identity
+                    let identity = Arc::new(NodeIdentity { line: 1, col: 1 });
+
+                    // 2. Build AST: (if true 42 nil)
+                    let ast = Node {
+                        identity: identity.clone(),
+                        kind: UntypedKind::If {
+                            cond: Box::new(Node {
+                                identity: identity.clone(),
+                                kind: UntypedKind::Constant(Value::Bool(true)),
+                            }),
+                            then_br: Box::new(Node {
+                                identity: identity.clone(),
+                                kind: UntypedKind::Constant(Value::Int(42)),
+                            }),
+                            else_br: Some(Box::new(Node {
+                                identity: identity.clone(),
+                                kind: UntypedKind::Constant(Value::Nil),
+                            })),
+                        },
+                    };
+
+                    // 3. Evaluate
+                    let mut context = Context {};
+                    let result = ast.eval(&mut context);
+
+                    self.output_log = format!(
+                        "AST Test:\nSource: (if true 42 nil)\nResult: {}\n\nCompiler log:\nStarted at {:?}",
+                        result,
+                        std::time::SystemTime::now(),
+                    );
+                }
+
+                ui.add_space(5.0);
+                ui.separator();
+                ui.label("Output / Logs:");
+
+                // Log Output Area
+                egui::ScrollArea::vertical()
+                    .id_salt("output_log_scroll")
+                    .show(ui, |ui| {
+                        ui.add_sized(
+                            ui.available_size(),
+                            egui::TextEdit::multiline(&mut self.output_log)
+                                .font(egui::TextStyle::Monospace)
+                                .desired_width(f32::INFINITY)
+                                .interactive(false), // Read-only
+                        );
+                    });
+            });
+
+        // Central Panel: Source Code Editor (Fills remaining space)
+        egui::CentralPanel::default().show(ctx, |ui| {
+            ui.heading("Source Code Editor");
+            ui.label("Input Source:");
+
+            egui::ScrollArea::vertical()
+                .id_salt("source_code_scroll")
+                .show(ui, |ui| {
+                    ui.add_sized(
+                        ui.available_size(),
+                        egui::TextEdit::multiline(&mut self.source_code)
+                            .font(egui::TextStyle::Monospace)
+                            .desired_width(f32::INFINITY)
+                            .lock_focus(true),
+                    );
+                });
+        });
+    }
+}