feat(bootstrap): thin-shell IntelliSDLC.ai-template repo (deferred from #136)

[MarkMichaelis]

Context

Issue #136 (closed by PR #141) covered the in-script bootstrap path: Pull-SDLC.ai.ps1 now auto-detects empty-state, auto-runs git init when needed, and exposes -RemoteUrl for org-portability. The README documents three recipes (existing repo, brand-new project, fork in another org) that all fully work today.

The original #136 plan also proposed a thin-shell GitHub template repo to make recipe C (brand-new project) a single gh repo create --template call. That layer was deferred; everything works without it.

Scope

Create IntelliTect-Samples/IntelliSDLC.ai-template as a thin shell:

1. Manual GitHub step -- create the repo with the Template repository flag enabled.
2. bootstrap.ps1 (~50 lines) -- runs once on a freshly-instantiated template clone:
   • Discovers the org via gh repo view --json templateRepository so a fork in Acme/IntelliSDLC.ai-template automatically points at Acme/IntelliSDLC.ai.
   • Downloads Pull-SDLC.ai.ps1 from the discovered sibling.
   • Invokes it with -RemoteUrl https://github.com/<org>/IntelliSDLC.ai.git.
   • Self-deletes; idempotent (no-op on re-run).
3. Template README -- one-paragraph "click Use this template, run ./bootstrap.ps1, done."
4. README update here -- replace recipe C with the gh repo create --template one-liner; demote the -RemoteUrl recipe to a fallback note.
5. E2E validation -- instantiate template into a scratch repo, confirm bootstrap completes and produces a working synced project.

Why deferred

• Recipe C via -RemoteUrl already covers the org-portability case.
• The template repo is a convenience layer (one gh call instead of two), not a capability gap.
• Creating the template repo is a manual GitHub step that cannot be automated from this codebase.

Refs

• Closes-out: feat(bootstrap): from-zero project bootstrap via thin-shell template + auto-detect in Pull-SDLC.ai.ps1 #136
• Depends on: PR feat(bootstrap): auto-detect empty-state and expose -RemoteUrl / -NoAutoInit #140 (auto-detect + -RemoteUrl) and PR docs(readme): add Onboarding section with three from-zero recipes #141 (README)