fix(scripts): make install.sh / build.sh work on stock macOS

Stock macOS ships bash 3.2 (frozen 2007 due to GPLv3) and BSD find.
Both scripts used `mapfile` (bash 4+) and `find -printf` (GNU only),
so a fresh Mac user running `bash scripts/install.sh` died on line 11
before copying anything. Replace with a portable shell glob — same
sort order, no `find` dependency, works on bash 3.2 and 4+.

Verified on git-bash: 16 skills discovered, install dry-run copies all,
`build.sh` produces a valid archive.

See .wiki/concepts/install-portability.md for the full gotcha.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.tasks/STATUS.md

@@ -14,6 +14,14 @@ _Updated: 2026-04-28_
     🔵 Blocked    — waiting on external input
 -->
 
+## 🟢 [mac-support-scripts] — fix install.sh / build.sh for stock macOS
+**Status:** done
+**Where I stopped:** patched both scripts to drop `mapfile` (bash 4+) and `find -printf` (GNU find) — replaced with portable shell glob + `basename` + `sort`; verified on git-bash (16 skills discovered, install dry-run + build smoke-test passed); wiki concept page `install-portability.md` added; index + log updated
+**Next action:** (none — kept until merged)
+**Branch:** master
+
+---
+
 ## 🟡 [skill-readmes] — write English README.md for every skill + translate root README
 **Status:** paused
 **Where I stopped:** infra-skill cluster done — READMEs for `project-bootstrap`, `setup-wiki`, `setup-tasks`, `using-wiki`, `using-tasks`; root README translated; cross-links between all five skills wired up