Bring the TUI diff footer onto the same terminator rule and distinct-path
count the Web DiffBlock uses (a trailing newline terminates its line; two
hunks in one file read as 1 file), so the two front ends' `+A -R · N file(s)`
footers agree. Reserve space in the diff path header for the floating copy
button so a long path no longer scrolls under it. Pass the tool's raw path to
the injected openFile (which already resolves against cwd) instead of resolving
twice. Rename the shared block-body CSS class to a card-neutral cardBody so a
terminal-spacing tweak cannot silently move the diff card. Add a same-file
two-hunk TUI unit test and an assembled built-boot assertion that the write
turn renders +1 -0 · 1 file end to end.