[pkg firewall] wire up endor-vscode.ps1 and document the ecosystem

[dekkagaijin]

Merge after #30

Final chunk. Completes the Windows side and adds the top-level documentation, which only becomes true once both platforms are in.

powershell/templates/vscode.ps1 the ecosystem template
powershell/templates/remove.ps1 watcher first, then unpatch per install
powershell/templates/script-header.ps1 -NoVSCodeWatcher
powershell/generate.ps1 gallery base, block assignment, repatch
payload builder
powershell/README.md per-script behaviour and prerequisites
package-firewall/README.md, README.md ecosystem tables, tests section

One behaviour here is worth reading closely. In repatch mode the template must NOT recompute the attributed token: the Scheduled Task can fire at startup with nobody logged in, so $ConsoleUser is empty there, and recomputing would mint a token attributed to no user at all — losing the attribution that makes firewall events traceable to a developer. The prelude reads the URL rendered at install time out of the sidecar state instead, and the template refuses to patch if that URL is empty rather than proceeding with a bad one.

The repatch payload is written from the base64 embedded at generation time, not copied from $PSCommandPath: MDM tools routinely run scripts from a temp file that is already gone by the time the task fires.

Also fixes stale documentation the VS Code work turned up, predating the user-attribution change: both READMEs conflated generation-time and install-time placeholders, listed NPM_AUTH_B64 / PYPI_URL / PIP_INDEX_URL / GO_PROXY_URL as generation-time when they are install-time fills, omitted the real API_SECRET_B64 and FQDN_HOST, and bash/README.md claimed env.sh still exports ENDOR_PYPI_URL.

Tests: 43 assertions over the generated PowerShell. The installer cannot run wholesale off-Windows — its header calls [WindowsIdentity]::GetCurrent() — so the header is stubbed and everything after it is extracted verbatim from the generated file and executed for real: block splitting, token construction, the patch loop, state writes, the watcher call, the repatch counter. The stub is deliberately narrow so what is not covered stays obvious. Among the assertions: the token is recomputed independently from the attribution scheme, and repatch is checked to reuse that same token rather than deriving a new one.

https://endorlabs.atlassian.net/browse/LM-452