Lands release step P3-F4-addrm on trunk. `zit add DIR` and `zit rm DIR` were hard errors directing the user to name individual files, which made `zit add .` and adding a source subtree dead ends. The increment makes both verbs recurse: `add DIR` expands over the already-shipped `extras.sweep` of the checkout root rather than introducing a second walker, so the exclusions, the no-follow symlink posture, and the tracked-set subtraction are the ones `addremove` and `clean` already use, with the sweep lazy and memoized so multiple directory arguments still perform one enumeration. `rm DIR` expands over the tracked keys via `ManagedSet.iterate` rather than over the disk, so an already-deleted directory remains forgettable. A single containment predicate, `pathUnderDir`, serves both verbs so the prefix-boundary case cannot diverge between them. Help text and exit-status wording now describe recursion instead of the removed directory error.

Merge evidence: `fossil merge release-0.1` reported no conflicts, updating only src/e2e.zig and src/main.zig; the tree carries no conflict markers (the open-marker occurrences that a grep turns up in src/merge3.zig and src/e2e.zig are that module's own conflict sentinel constant and the tests asserting on it, not merge residue). The merged tree — not merely the branch — was re-verified green on trunk after the merge: `zig fmt --check .`, `zig build`, and `zig build test` all exit 0. `fossil extras` is empty, so the merge adds no file it fails to track.

No borrowed techniques in this change, so no attribution is owed. check-in: fca1e073c2 user: dmestas tags: trunk