feat(project-bootstrap): add we're on Windows to default CLAUDE.md template

Pin every newly-bootstrapped project to Windows / PowerShell out of the box
by adding a fifth trigger line to the CLAUDE.md template. The line activates
the active-platform skill, which then governs all command/example output.

- skills/project-bootstrap/assets/CLAUDE.md.template: append `we're on Windows`
- skills/project-bootstrap/SKILL.md: sync the embedded preview in Step 5 and
  document the Linux/macOS substitution
- CLAUDE.md (this repo): backfill the line — was created from old template
- dist/project-bootstrap.skill: rebuilt
- .wiki/source/active-platform-decision.md: append "Wired into project-bootstrap"

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

.wiki/source/active-platform-decision.md

@@ -26,6 +26,12 @@ Full spec: [`skills/active-platform/SKILL.md`](../../skills/active-platform/SKIL
 - **Cross-repo:** installed into `~/.claude/skills/`, applies in every session regardless of project.
 - **Iterable:** lives in this repo's `skills/` so we can edit + reinstall as we learn what triggers and exceptions actually happen in practice.
 
+## Wired into `project-bootstrap`
+
+The default platform should travel with every new project we create. Updated `project-bootstrap` so its `CLAUDE.md.template` adds a fifth trigger line: `we're on Windows`. That line is one of `active-platform`'s recognized switches, so any project bootstrapped from now on starts pinned to Windows / PowerShell. If the user is bootstrapping on a Linux/macOS host, the `SKILL.md` Step 5 note tells them to swap the line for `we're on Linux` / `we're on macOS`.
+
+Backfilled the same line into this repo's own `CLAUDE.md` (which was created from the old template).
+
 ## Open questions to revisit
 
 - Are the trigger phrases comprehensive enough? Add real-world examples as they come up.