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, 2 insertions, 1 deletions

diff --git a/src/detached/server.zig b/src/detached/server.zig
index 212c9a3d..46fb8fcf 100644
--- a/src/detached/server.zig
+++ b/src/detached/server.zig
@@ -739,7 +739,7 @@ pub const Session = struct {
 
     fn sendFrame(s: *Session, c: *Client, surface: *const pardes.Surface) void {
         const cells = surface.cells;
-        const want = wire.frameBound(surface.cols, surface.rows) + wire.layersBound(&surface.body_layers, &surface.tag_layers);
+        const want = wire.frameBound(surface.cols, surface.rows) + wire.layersBound(&surface.body_layers, &surface.tag_layers, surface.regionList());
         s.scratch.ensureTotalCapacity(s.gpa, want) catch return s.close(c, .oom);
         const prev: []const pardes.Cell = if (c.need_full or c.mirror.items.len != cells.len)
             &.{}
@@ -759,6 +759,7 @@ pub const Session = struct {
             prev,
             &surface.body_layers,
             &surface.tag_layers,
+            surface.regionList(),
         ) catch |err| {
             log.debug("frame {d}x{d} not encodable: {t}", .{ surface.cols, surface.rows, err });
             return;