Make the column and workspace tags Texts with the pane tag's keys

The headers had their own one-line editor with its own keys: Enter always
executed, h/l and J/K moved between headers and panes, Ctrl-c/x/v cut and
pasted, and TagLine refused a newline that 9P accepted. They are now Texts
like a pane's tag, with no prefix and a default until edited, so normal and
insert mode, undo and the look and execute keys are the body's. Moving
between them is the window keys' job: Up from a pane with nothing above it
reaches its column's tag and then the workspace's, Down comes back, and
Left and Right walk the column tags.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/File.zig b/src/File.zig
index 2bf9f57d..22e3c434 100644
--- a/src/File.zig
+++ b/src/File.zig
@@ -654,6 +654,7 @@ pub fn cursorLines(arena: std.mem.Allocator, pane: *Pane, f: *State) ![]const []
 /// Use the file's line index only when `text` is its complete live content.
 /// Edit-buffer fragments and other temporary text retain modal's scan path.
 fn contentIndex(t: *Text, text: []const u8) ?[]const usize {
+    if (t.what != .body) return null;
     const pane = t.pane();
     const f = if (pane.file) |*file| file else return null;
     if (text.ptr != f.content.ptr or text.len != f.content.len) return null;