po: adopt --no-wrap policy for all translation catalogs - #61

Summary

Adopts --no-wrap as the project-wide formatting policy for all translation catalogs, following the discussion in #59 (@ngosang, @mrjimenez, me — all in agreement). The default 77-char wrap is a TTY-era convention; nobody hand-edits raw .po files anymore for a Weblate-managed project, and the wrap mostly buries real translation changes under reflow noise — PR #59's own diff is the canonical example.

This PR makes the switch coherent end-to-end on the repo side. The remaining piece — flipping the Weblate components to "Do not wrap long lines" — is on @ngosang after this lands.

Rebased onto master after #60. The pre-#60 version of this PR had identical scope and content.

Tooling changes (commit 1, +24/-7)

• scripts/update-po.sh — pass --no-wrap to xgettext and msgmerge, and rewrite each .po via --output-file=$tmp && mv $tmp $orig instead of --update. msgmerge --update treats a .po as up-to-date when only the pot's wrap (not its content) has changed and silently skips rewriting, which defeats --no-wrap on any catalog previously committed in wrapped form. The tempfile pattern always rewrites.
• po/Makevars — add --no-wrap to XGETTEXT_OPTIONS for symmetry with the legacy autotools update-po target (CMake doesn't currently invoke it, but the values stay consistent).
• docs/man/po4a.config — add --wrap-po no to the global [options] line; po4a's equivalent of gettext's --no-wrap for the manpages catalogs. Rendered .1.in output is unaffected (po4a's content reflow is governed by --width, which we don't touch).
• .github/workflows/i18n.yml pot-sync drift check — simplify the comparison normalisation from msgcat --width=79 to msgcat --no-wrap. The check stays wrap-policy-agnostic by design (it normalises both sides), but --no-wrap now matches the policy and is one knob simpler.

One-shot normalisation (commit 2, +7626/-21227)

Regenerated po/amule.pot + all po/*.po with the new script (bulk of the diff). Each msgid/msgstr collapses from multi-line continuation strings to a single line. No translations gained or lost, no fuzzy or obsolete markings introduced. The docs/man/po/manpages-*.po files were already in no-wrap-equivalent form on master, so only docs/man/po/manpages.pot was rewritten by the po4a pass; no rendered .1.in file changed.

Drive-by: po/gl.po was 100755 on master (the only .po with the executable bit set, an old accidental mode). The regen writes through a tempfile + mv and reseats it to 100644, matching every other catalog.

The drift check (msgcat --no-wrap, strip volatile headers + #: source refs) passes cleanly across all catalogs locally.

Test plan

• CI green on this branch (pofiles, pot-sync, manpages-sync).
• After merge: @ngosang flips Weblate's application + application-man-pages components to "Do not wrap long lines"; next bot PR should be content-only.