Lift takes a style: shadow, surface, rim, glow or auto

The user wants Lift to read on dark themes, where a shadow has nothing to
darken. `Lift shadow|surface|rim|glow|auto` (`on` is auto, bare flips
auto and off): surface lightens the lifted part's ground about 5.5%
(Material-dark), rim is a thin soft light off its top and left edges,
glow a faint halo in the theme's accent (Chrome.accent, the focused box
colour), auto a shadow on a light page and surface with half a rim on a
dark one (by the page's luminance). Rim and glow are the soft kernel in a
light colour (no pre-warp: coloured light is laid on as is, within §8.2's
budget); each style is capped per theme so text keeps min(its contrast,
4.5) (tests: darkening and lightening over the native themes). The style
travels in the palette (Chrome.lift_style, one byte on the wire). Config
reports and ctl reads `Lift <style>`.

Shared files touched: config.zig, builtins.zig, ninep/ctl.zig,
detached/wire.zig (palette byte), gui.zig. Not touched: pardes.zig,
Messages.zig, mouse.zig.

1 files changed, 5 insertions, 3 deletions

diff --git a/src/draw.zig b/src/draw.zig
index 70b629a5..98932c23 100644
--- a/src/draw.zig
+++ b/src/draw.zig
@@ -128,12 +128,12 @@ pub fn place(p: *Pardes, s: *Surface) void {
             spring.* = .{};
         }
         // At this frame's own time, not the stepped animations' 16 ms grid.
-        spring.retarget(if (p.settings.lift and id == p.active) 1 else 0, p.now_ns);
+        spring.retarget(if (p.settings.lift != .off and id == p.active) 1 else 0, p.now_ns);
         _ = spring.step(p.now_ns);
     }
     for (s.regions[0..s.nregions]) |*region| switch (region.kind) {
         .grip, .tag, .body, .rail => region.lift = p.lifts[region.owner].value(p.now_ns),
-        .notice => region.lift = if (p.settings.lift) 1 else 0,
+        .notice => region.lift = if (p.settings.lift != .off) 1 else 0,
         else => {},
     };
     if (p.drag == .column_move) rail: {
@@ -200,6 +200,8 @@ pub fn render(p: *Pardes, arena: std.mem.Allocator) !*Surface {
         .tag_fg = chrome.tag_fg,
         .scroll_track = chrome.scroll_track,
         .scroll_thumb = chrome.scroll_thumb,
+        .accent = chrome.box,
+        .lift_style = @intFromEnum(p.settings.lift),
     };
     place(p, s);
     // Separators have their own role; a scrollbar need not frame the page.
@@ -1133,7 +1135,7 @@ test "a lift is sampled at each frame's own time, and asks for frames only while
     p.advance(1000 * ms);
     _ = try p.render(arena.allocator());
     try std.testing.expect(!p.continuous());
-    p.settings.lift = true;
+    p.settings.lift = .shadow;
     var lifts: [3]f32 = undefined;
     // 144 Hz: 6.9 ms apart, none of them on a 16 ms step of its own.
     for (&lifts, 0..) |*lift, i| {