feat: add theme selection palette

Also, refactor to share palette code and make palettes scroll properly
with the mouse wheel.

src/tui/mode/overlay/theme_palette.zig

@@ -0,0 +1,65 @@
+const std = @import("std");
+const cbor = @import("cbor");
+const tp = @import("thespian");
+
+const Widget = @import("../../Widget.zig");
+const tui = @import("../../tui.zig");
+
+pub const Type = @import("palette.zig").Create(@This());
+
+pub const label = "Search themes";
+
+pub const Entry = struct {
+    name: []const u8,
+};
+
+pub const Match = struct {
+    name: []const u8,
+    score: i32,
+    matches: []const usize,
+};
+
+var previous_theme: ?[]const u8 = null;
+pub fn load_entries(palette: *Type) !void {
+    previous_theme = tui.current().theme.name;
+    for (Widget.themes) |theme| {
+        (palette.entries.addOne() catch @panic("oom")).* = .{
+            .name = theme.name,
+        };
+    }
+}
+
+pub fn add_menu_entry(palette: *Type, entry: *Entry, matches: ?[]const usize) !void {
+    var value = std.ArrayList(u8).init(palette.a);
+    defer value.deinit();
+    const writer = value.writer();
+    try cbor.writeValue(writer, entry.name);
+    try cbor.writeValue(writer, if (palette.hints) |hints| hints.get(entry.name) orelse "" else "");
+    if (matches) |matches_|
+        try cbor.writeValue(writer, matches_);
+    try palette.menu.add_item_with_handler(value.items, select);
+    palette.items += 1;
+}
+
+fn select(menu: **Type.MenuState, button: *Type.ButtonState) void {
+    var name: []const u8 = undefined;
+    var iter = button.opts.label;
+    if (!(cbor.matchString(&iter, &name) catch false)) return;
+    tp.self_pid().send(.{ "cmd", "exit_overlay_mode" }) catch |e| menu.*.opts.ctx.logger.err("theme_palette", e);
+    tp.self_pid().send(.{ "cmd", "set_theme", .{name} }) catch |e| menu.*.opts.ctx.logger.err("theme_palette", e);
+}
+
+pub fn updated(palette: *Type, button_: ?*Type.ButtonState) !void {
+    const button = button_ orelse return cancel(palette);
+    var name: []const u8 = undefined;
+    var iter = button.opts.label;
+    if (!(cbor.matchString(&iter, &name) catch false)) return;
+    tp.self_pid().send(.{ "cmd", "set_theme", .{name} }) catch |e| palette.logger.err("theme_palette upated", e);
+}
+
+pub fn cancel(palette: *Type) !void {
+    if (previous_theme) |name| if (!std.mem.eql(u8, name, tui.current().theme.name)) {
+        previous_theme = null;
+        tp.self_pid().send(.{ "cmd", "set_theme", .{name} }) catch |e| palette.logger.err("theme_palette cancel", e);
+    };
+}