One Layer for tags, notices, headers and bodies; a taller tag is one layer of rows; wire v8

src/Layer.zig merges TagLayer and BodyLayer. `rows` (0 = no layer) and a
cursor at {x, y}. A tag of N rows is ONE layer of N grid rows: tagHit answers
the row as `line`, bodyHit keeps its meaning, and the per-line layer bases
(TAG_LINE_LAYER_BASE, HEADER_LINE_LAYER_BASE) are gone, not aliased.

Wire v8, the one bump: tag layers carry rows and cursor y, and the frame
carries the placed region list. v7 and v9 peers are refused in both
directions (server test over both, a new frontend test over both).

web: tag_layer_value 11 = rows, 12 = cursor y; app.mjs lays every row.
macOS: the Zig side compiles against Layer; pardes.h still sees one row
per tag layer (accepted, the macOS shell is ignored for now).

No visual change: snapshot goldens and the 17 GUI goldens byte-identical.

Shared files touched: pardes.zig, Messages.zig, gui.zig, macos.zig,
detached/client.zig, detached/server.zig, detached/wire.zig (plus web.zig,
app.mjs, edit.zig, look.zig). Not touched: mouse.zig, tagline.zig,
colors.zig, tty.zig, dump.zig, exec.zig, host_io.zig, panes.zig.

1 files changed, 5 insertions, 5 deletions

diff --git a/test/column_drag.zig b/test/column_drag.zig
index feea1bf7..3aea4286 100644
--- a/test/column_drag.zig
+++ b/test/column_drag.zig
@@ -8,17 +8,17 @@ fn mouse(p: *Pardes, kind: pardes.Mouse.Kind, col: u16) void {
     p.update(.{ .mouse = .{ .button = .left, .kind = kind, .col = col, .row = pardes.TOPBAR_H } });
 }
 
-fn tagLayer(p: *Pardes, column: usize) !*pardes.TagLayer {
+fn tagLayer(p: *Pardes, column: usize) !*pardes.Layer {
     for (&p.surface.tag_layers) |*layer| {
-        if (layer.cols > 0 and layer.kind == .column and layer.id == column) return layer;
+        if (layer.rows > 0 and layer.kind == .column and layer.id == column) return layer;
     }
     return error.MissingColumnTagLayer;
 }
 
-fn headerMouse(layer: *const pardes.TagLayer, display_col: u16, kind: pardes.Mouse.Kind) pardes.Mouse {
+fn headerMouse(layer: *const pardes.Layer, display_col: u16, kind: pardes.Mouse.Kind) pardes.Mouse {
     const x = @as(f32, @floatFromInt(layer.viewport.x)) * 10 + (@as(f32, @floatFromInt(display_col)) + 0.5) * 5;
     const y = (@as(f32, @floatFromInt(layer.viewport.y)) + 0.5) * 20;
-    return .{ .button = .left, .kind = kind, .col = @intFromFloat(x / 10), .row = @intFromFloat(y / 20), .tag_hit = layer.hitAt(x, y, 10, 20, 5, 10) };
+    return .{ .button = .left, .kind = kind, .col = @intFromFloat(x / 10), .row = @intFromFloat(y / 20), .tag_hit = layer.tagHit(x, y, 10, 20, 5, 10) };
 }
 
 const Snapshot = struct {
@@ -144,7 +144,7 @@ test "column grip is separate from compact text and the resize seam" {
         try std.testing.expectEqual(p.col_x[column], rect.x);
         try std.testing.expectEqual(rect.x + pardes.TAG_TEXT_INSET, (try tagLayer(p, column)).viewport.x);
         for (p.surface.tagLayers()) |pane_layer| {
-            if (pane_layer.cols > 0 and pane_layer.kind == .pane and pane_layer.id == pane_id)
+            if (pane_layer.rows > 0 and pane_layer.kind == .pane and pane_layer.id == pane_id)
                 try std.testing.expectEqual((try tagLayer(p, column)).viewport.x, pane_layer.viewport.x);
         }
         const pane_tag_y = if (p.settings.tag_bottom) rect.y + rect.h - pardes.BOX_H else rect.y;