feat: add while loops, break and continue statements

PLAN.md

@@ -45,29 +45,37 @@ A Rust-flavored, C-targeting language - built pipeline-first.
 - [x] Output System V AMD64 ABI-compliant `.o` machine code files
 - [x] End-to-end test: compile a simple `fn` → link via `gcc` → run → correct exit code
 
+## Phase 5 - The Ray Tracer Milestone (Current)
+
+To successfully write a simple ray tracer, we need continuous math, data structures, and I/O. The following path establishes these prerequisites:
+
+- [ ] **Floating-Point Support:** Add `f32`/`f64` types, decimal literals, and Cranelift lowering for `fadd`, `fmul`, etc.
+- [ ] **FFI & Interop:** Implement `extern fn` declarations to bind C standard library functions (like `putchar` or `printf`) for `.ppm` image output.
+- [ ] **Type Casting:** Add the `as` operator to convert floating-point color bounds `[0.0, 1.0]` into integer byte formats `[0, 255]`.
+- [ ] **Pointers:** Add pointer types (`*T`), address-of (`&`), and dereference (`*`) operators.
+- [ ] **Structs:** Add `struct` definitions, initializers, and field access (`ray.origin.x`) to represent 3D vectors, rays, and spheres.
+- [ ] **Arrays:** Add fixed-size arrays (`[T; N]`) or heap allocations for the scene and framebuffers.
+
 ## Planned Features (Backlog)
 
-### Control flow
+### Control flow & Variables
 - [x] booleans and comparision operators
 - [x] `if` / `else` branching
-- [ ] `while` loops
+- [x] `while` loops, `break`, `continue`
+- [x] `let` bindings and variable assignments
 
 ### Types & memory
-- [ ] Typed pointers (`*T`)
 - [ ] Opaque pointers (`*void` / `*opaque`)
-- [ ] Raw pointer arithmetic & dereference
-- [ ] Fixed-size arrays (`[T; N]`)
+- [ ] Raw pointer arithmetic
 - [ ] Slices (`&[T]` / `[]T`)
 
 ### Composite types
-- [ ] Structs & field access
 - [ ] Enums (C-style tagged unions)
 - [ ] Pattern matching (`match` / `switch`)
 
 ### Strings & interop
-- [ ] String literals & `*u8` handling
+- [ ] String literals
 - [ ] Variadic functions (for `printf` interop)
-- [ ] `extern` / FFI declarations
 
 ### Tooling & backend
 - [ ] Proper register allocator