Fix security vulnerabilities (#767)

* fix: resolve npm audit vulnerabilities, refresh license cache, rebuild dist

- npm audit fix resolves brace-expansion (high), fast-xml-parser (high),
  and undici (moderate) advisories via transitive dependency updates
- Regenerated .licenses/npm cache to match updated dependency tree
- Rebuilt dist/setup and dist/cache-save bundles

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: sync vendored install-dotnet.ps1 with upstream dot.net script

Basic Validation was failing because the vendored copy of
externals/install-dotnet.ps1 was out of date compared to the live
script served from https://dot.net/v1/dotnet-install.ps1, which
installation-scripts.test.ts compares against on every run.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.licenses/npm/brace-expansion-5.0.9.dep.yml

@@ -0,0 +1,34 @@
+---
+name: brace-expansion
+version: 5.0.9
+type: npm
+summary: Brace expansion as known from sh/bash
+homepage:
+license: other
+licenses:
+- sources: LICENSE
+  text: |
+    MIT License
+
+    Copyright Julian Gruber <julian@juliangruber.com>
+
+    TypeScript port Copyright Isaac Z. Schlueter <i@izs.me>
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+notices: []