Generalize USMT Dash and add a containerized demo mode

Remove all environment-specific data and make the dashboard adoptable
anywhere, then add a demo that runs the real PowerShell services.

- Strip cached device data, internal knowledge-base articles and
  screenshots, server/site names and the old project notes; replace the
  knowledge base with generic sample articles and diagrams
- Move every environment value into Config/usmt-dash.psd1
- Route all infrastructure access in the worker and Get-Software.ps1
  through a provider (Providers/SCCM.ps1), with a config-driven asset
  inventory view instead of a hard-coded custom class
- Add Providers/Demo.ps1: a deterministic simulated fleet whose
  migrations progress in real time, and Demo/New-DemoData.ps1 to seed it
- Server: -Demo makes the API read-only; add get-config and get-logs;
  serve static files only from web/, Documentation/ and an allowlist of
  Data/ files with a path-traversal guard; gzip large responses
- Mirror both services' console output to Data/Logs via a Write-Host
  proxy, and add a terminal panel to the dashboard that streams it
- Demo sandbox (web/demo/demo.js): visitor changes to tags, articles and
  images are kept in the visitor's browser and echoed in the terminals;
  nothing a visitor does reaches the server
- Vendor marked, highlight.js and html2pdf.js instead of loading CDNs
- Dockerfile and compose file for hosting the demo (Coolify-ready)

Documentation/Microsoft Teams.md

@@ -0,0 +1,21 @@
+[[Green:Baseline]]
+
+# Microsoft Teams
+
+The new Teams client is provisioned per user. It installs automatically the first time a user signs in to a device built from the standard image.
+
+## Checks After Migration
+1. Teams launches and signs in without prompting for a password (SSO).
+2. **Settings > Devices**: the correct headset/camera is selected.
+3. The **Teams Meeting Add-in** appears in Outlook's ribbon.
+
+## Meeting Add-in Missing in Outlook
+1. Close Outlook and Teams.
+2. Start Teams, wait for it to fully load, then start Outlook.
+3. If still missing: Outlook > File > Options > Add-ins > Manage **COM Add-ins** > Go > enable *Microsoft Teams Meeting Add-in*.
+
+## Clear the Teams Cache
+```powershell
+Get-Process ms-teams -ErrorAction SilentlyContinue | Stop-Process -Force
+Remove-Item "$env:LocalAppData\Packages\MSTeams_8wekyb3d8bbwe\LocalCache\Microsoft\MSTeams" -Recurse -Force
+```