merge: twelve parallel changes — bug fixes, features, posix port — plus three merge-state fixes born of branch interactions.

Branch work merged: tty exit cleanup (krluslzz), drag-select effect-queue crash (zopqvlll), single-pane layout rule (tutmotnl), tty input coalescing + -Dtracy (olnvomwz), / file search (syqzvmkl) + generalized n/N look motion (nmzypsto), ghostty middle-click diagnosis (sqonpmsz), NOR/INS/TTY mode indicators (opmrortk), cursor-row gutter highlight (nymrwpwq), look path:NN centering (oktvtuss), scrolloff (wlqqyvvo), posix portability (pzwluyuw).

Merge-state fixes: (1) splitBelow caps keep at body-(BOX_H+3) so a content-full source still leaves the new pane a tag + a few body rows — Alt-n from a full shell was born 0 rows tall (caught by ttylook: OVER marker had no rows to render in). (2) spawn-effect pane-id reuse crash (user-reported panic at drainEffects assert): no close effect exists, so a deleted pane pty lingers in its slot until a respawn lands on it — both shells now reap the stale pty at spawn (tty: cancel reader + close; gui: SIGKILL, reader delivers the old fd through the eof event) and per-slot generations drop the dead shell late output/eof, which otherwise nuked the NEW pty on the reused id. New respawn.snap golden; fails on the pre-fix assert. (3) dedup re-look now lands the modal cursor on the target line (cur_row/cur_col/cur_pinned) — scrolloff cursor-anchored reconcile otherwise yanked the recentered view back to the stale cursor (caught auditing look-center: center-dedup stayed at 97-102 instead of 146-154); this is also the requested focus-moves-cursor behavior. look-center dedup/clamp clicks re-aimed for the merged layout geometry (typed row moved from 18 to 15).

Goldens reconciled by regenerating from the merged binary and auditing every diff against its origin branch; deltas are exactly: indicator text/width shift, layout-split pane sizing, cursor-row gutter styling, centering shifts, and the pane-edge hover dash now coinciding with new pane boundaries. Suite: 28/28 (27 + respawn).