Reorganize: scripts under scripts/, add README disclaimer

- Move _template.ps1 and cg-disable.ps1 into scripts/
- Update all fetch/run URLs and doc links to scripts/ paths
- Rework README layout/naming section; add as-is/no-warranty disclaimer

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CONTRIBUTING.md

@@ -44,7 +44,7 @@ split the particular out to the private tier and reference it as a placeholder.
 
 ## Scripts
 
-Follow [`_template.ps1`](_template.ps1):
+Scripts live under `scripts/`. Follow [`scripts/_template.ps1`](scripts/_template.ps1):
 
 - Prompt for placeholders with `Read-Host` — no editing before running, no
   `param()` (can't pass args through `irm | iex`).