structure: backends into src/{tty,gui,lsp}, pane kinds and builtins into their own files

The core now lies FLAT at src/ and every subdirectory is one backend, so a
file being in no directory at all is what says it is core. Pane-kind bodies
leave pardes.zig for term_pane.zig / file_pane.zig / output_pane.zig, leaving
it the layout, the event/effect machine and the generic render loop.

Builtins are one struct each in builtins.zig, and the enum is folded out of
the file's own declaration list at comptime — a zig file IS a struct, so the
list of builtins and the builtins themselves are the same text. Adding one is
writing a struct. Key paths deliberately stay one table for the config pass.

Pure refactor: no golden moved.

1 files changed, 0 insertions, 43 deletions

diff --git a/src/crt.zig b/src/crt.zig
deleted file mode 100644
index 9cf81593..00000000
--- a/src/crt.zig
+++ /dev/null
@@ -1,43 +0,0 @@
-//! The Crt builtin's screen geometry, shared between the gui shell's input
-//! mapping and its shader: crt.frag.glsl shows the scene point
-//! uv' = cc*(1 + barrel*r2) at screen point cc, so a physical mouse position
-//! must pass through the SAME forward transform before it becomes a cell.
-//! Pure std, so the unit-test step can pin it against the shader formula.
-
-const std = @import("std");
-
-/// MUST match BARREL in shaders/crt.frag.glsl
-pub const barrel: f32 = 0.012;
-
-pub const Point = struct { x: f32, y: f32 };
-
-/// physical window pixels -> the scene pixels the shader displays there,
-/// clamped to the window. The shader's phosphor quantization and chromatic
-/// offset displace at most a few pixels — well under a cell — and are
-/// ignored here.
-pub fn map(x: f32, y: f32, w: f32, h: f32) Point {
-    const ccx = x / w * 2.0 - 1.0;
-    const ccy = y / h * 2.0 - 1.0;
-    const s = 1.0 + barrel * (ccx * ccx + ccy * ccy);
-    return .{
-        .x = std.math.clamp((ccx * s + 1.0) * 0.5 * w, 0, w - 1),
-        .y = std.math.clamp((ccy * s + 1.0) * 0.5 * h, 0, h - 1),
-    };
-}
-
-test "map matches the shader's barrel formula" {
-    // center is a fixed point
-    try std.testing.expectApproxEqAbs(@as(f32, 500), map(500, 250, 1000, 500).x, 0.001);
-    try std.testing.expectApproxEqAbs(@as(f32, 250), map(500, 250, 1000, 500).y, 0.001);
-    // corners: cc=(±1,±1), r2=2, scale 1.024 pushes past the tube -> clamped
-    try std.testing.expectEqual(@as(f32, 0), map(0, 0, 1000, 500).x);
-    try std.testing.expectEqual(@as(f32, 0), map(0, 0, 1000, 500).y);
-    try std.testing.expectEqual(@as(f32, 999), map(1000, 500, 1000, 500).x);
-    try std.testing.expectEqual(@as(f32, 499), map(1000, 500, 1000, 500).y);
-    // (100,100) of 1000x500: cc=(-0.8,-0.6), r2=1.0, s=1.012 ->
-    // cc'=(-0.8096,-0.6072) -> (95.2, 98.2)
-    try std.testing.expectApproxEqAbs(@as(f32, 95.2), map(100, 100, 1000, 500).x, 0.01);
-    try std.testing.expectApproxEqAbs(@as(f32, 98.2), map(100, 100, 1000, 500).y, 0.01);
-    // (900,250): cc=(0.8,0), r2=0.64, s=1.00768 -> x'=903.072
-    try std.testing.expectApproxEqAbs(@as(f32, 903.072), map(900, 250, 1000, 500).x, 0.01);
-}