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, 22 insertions, 0 deletions

diff --git a/src/themes/dark.zig b/src/themes/dark.zig
new file mode 100644
index 00000000..df418982
--- /dev/null
+++ b/src/themes/dark.zig
@@ -0,0 +1,22 @@
+//! pardes's own dark theme, and the boot default until the helix capture
+//! displaced it. It stays in the ring because it is the only one that leaves
+//! `bg`/`fg` NULL: the page keeps the host terminal's own default cell, so
+//! pardes sits inside whatever the surrounding terminal already looks like and
+//! only paints its chrome. Every other theme here dresses the whole page.
+pub const theme = .{
+    .name = "dark",
+    .bg = null,
+    .fg = null,
+    .tag_bg = .{ 0x2c, 0x2a, 0x3e },
+    .tag_fg = .{ 0x96, 0x96, 0x96 },
+    .box = .{ 0x6e, 0x4f, 0xd0 },
+    .box_dim = .{ 0x38, 0x3c, 0x54 },
+    .kw = .{ 0xcc, 0x70, 0xd8 },
+    .str = .{ 0x8a, 0xb8, 0x7a },
+    .num = .{ 0xd0, 0xc0, 0x70 },
+    .comment = .{ 0xf0, 0xf0, 0xf0 },
+    .lineno = .{ 0x5a, 0x5a, 0x5a },
+    .scroll_track = .{ 0x2a, 0x2a, 0x2a },
+    .scroll_thumb = .{ 0x52, 0x52, 0x52 },
+    .palette = null,
+};