themes: one file each, generated from helix and zed, picked by stepping a list

Each theme is a .zig file of pure data and nothing enumerates them by hand —
fold() walks the container's declarations, so a theme is a file and that is the
whole registration. Field by field rather than a wholesale coercion, which
makes a missing field a compile error that names it.

tools/gen_themes.zig reads helix .toml and zed .json out of vendor/themes and
emits one .zig each; build.zig reads that directory, so adding a theme is
dropping a file in. Output goes to the build cache rather than the tree, so zig
owns the freshness check and a deleted source cannot leave a stale theme
behind. Vendored, not read from the genizah: the build stays offline. A source
it cannot map is a hard error naming the file and the key, never a silently
black-on-black theme.

ThemeSel is the clever half. Traits gained an `executes` column, so n/N over
that buffer hands the whole line to Exec instead of the leading word to Look —
both arms the ordinary builtin, so a stepped row does exactly what the matching
mouse button on it would. Stepping the list previews each theme live. The trait
is a pane property, not an output-pane branch, so any pane whose lines are
commands can opt in.

Goldens: leader gains SPC t t; theme's fourth NextColor no longer wraps to
helix because the ring is fifteen long. New: themesel.

1 files changed, 29 insertions, 0 deletions

diff --git a/src/themes/acme.zig b/src/themes/acme.zig
new file mode 100644
index 00000000..925cacfb
--- /dev/null
+++ b/src/themes/acme.zig
@@ -0,0 +1,29 @@
+//! acme's yellow page — the light theme, and the one that has to resolve
+//! `palette` itself. A theme that only dresses the page can leave a child's
+//! ANSI indices alone and let the host answer them; on #ffffea that is how you
+//! get pale yellow `ls` output on pale yellow paper. So the sixteen below are
+//! darkened for paper: index 7 (the "white" a shell writes most of its output
+//! in) is a mid grey, and 15 (bright white) is BLACK, because a program asking
+//! for the brightest color on a light page means "make this stand out".
+pub const theme = .{
+    .name = "acme",
+    .bg = .{ 0xff, 0xff, 0xea },
+    .fg = .{ 0x00, 0x00, 0x00 },
+    .tag_bg = .{ 0xea, 0xff, 0xff },
+    .tag_fg = .{ 0x00, 0x00, 0x00 },
+    .box = .{ 0x6e, 0x4f, 0xd0 },
+    .box_dim = .{ 0x38, 0x3c, 0x54 },
+    .kw = .{ 0x88, 0x22, 0x99 },
+    .str = .{ 0x00, 0x77, 0x33 },
+    .num = .{ 0xa0, 0x52, 0x00 },
+    .comment = .{ 0x55, 0x55, 0x55 },
+    .lineno = .{ 0x99, 0x99, 0x80 },
+    .scroll_track = .{ 0x99, 0x99, 0x4c },
+    .scroll_thumb = .{ 0xff, 0xff, 0xea },
+    .palette = .{
+        .{ 0x00, 0x00, 0x00 }, .{ 0xaa, 0x22, 0x22 }, .{ 0x22, 0x80, 0x22 }, .{ 0x88, 0x66, 0x00 },
+        .{ 0x22, 0x44, 0xbb }, .{ 0x99, 0x33, 0x99 }, .{ 0x11, 0x88, 0x88 }, .{ 0x55, 0x55, 0x55 },
+        .{ 0x88, 0x88, 0x88 }, .{ 0xcc, 0x33, 0x33 }, .{ 0x33, 0xaa, 0x33 }, .{ 0xaa, 0x77, 0x00 },
+        .{ 0x33, 0x55, 0xdd }, .{ 0xbb, 0x44, 0xbb }, .{ 0x22, 0xaa, 0xaa }, .{ 0x00, 0x00, 0x00 },
+    },
+};