feat: add active-platform skill (Win/Linux/macOS switcher)

- skills/active-platform/SKILL.md: default = Windows/PowerShell; trigger
  phrases in RU+EN switch the active platform for the session; per-platform
  conventions (chaining, paths, env vars, install scripts) documented
- dist/active-platform.skill: built archive
- .wiki/source/active-platform-decision.md: rationale (skill chosen over
  global CLAUDE.md / project memory; user wanted a discoverable, iterable
  artifact)
- scripts/build.sh: fix PS arg-passing — single-quotes were leaking into
  -Names value, so multi-arg builds on Windows were rejected with
  "not found in skills/"

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

.tasks/STATUS.md

@@ -3,6 +3,13 @@ _Updated: 2026-04-28_
 
 ## Done
 
+### active-platform skill
+- [x] Draft `skills/active-platform/SKILL.md` (RU+EN triggers, default=Windows/PowerShell, palette=Win/Linux/mac)
+- [x] Fixed `build.sh` PS arg-passing bug (single-quotes were leaking into `-Names` value)
+- [x] Build `dist/active-platform.skill` and install into `~/.claude/skills/`
+- [x] Document decision in `.wiki/source/active-platform-decision.md`
+- [x] Update `.wiki/SUMMARY.md`
+
 ### bootstrap-skills-migration
 - [x] Bootstrap repo (git, .wiki, .tasks, CLAUDE.md)
 - [x] Brainstorm and document repo layout (`.wiki/source/repo-layout.md`)
@@ -20,3 +27,5 @@ _Updated: 2026-04-28_
 - Consider a PowerShell-native `install.ps1` (current `install.sh` already works in git-bash, so low priority).
 - Revisit grouping/manifest if skill count grows past ~30.
 - Decide whether to write a smoke-test that round-trips `skills/<name>/` → `dist/<name>.skill` → unpack → diff (would catch archive-shape regressions).
+- Tune `active-platform` triggers based on real-world usage; add WSL handling if it comes up.
+- Consider running formal `skill-creator` eval loop on `active-platform` once we have ~5 real interactions to learn from.