Make main the lean product a site receives

main was 16 days and 259 commits behind the line the product is actually built
on, at contract 0.30.0 against 0.35.0, with no per-PC credential code at all. It
was neither current nor curated - just stale. This brings it forward and, at the
same time, makes it mean something: main is what a receiving site installs, and
nothing else.

WHAT IT CARRIES. Twelve plugins - backups, computers, endpoints, guides,
knowledgebase, machines, network, notifications, printers, slides, tools,
warranty - plus applications, which is manifest-less core and always ships. The
only manifest dependency inside that set is endpoints on computers, and both are
in it, so the closure is self-contained.

WHAT IT DOES NOT. employees, geenforce, measuringtools, printedparts and usb
stay on the site line. So do the Windows installer tree, the VM rehearsal
helpers, the agent tooling config, one site's data loader, the internal audit
and findings records, and the planner spreadsheet. 1,135 tracked files against
1,438.

A REMOVAL THAT BREAKS THE APP IS NOT A REMOVAL, and two nearly shipped:

deploy/site-profile-universal.json still named all seventeen plugins. It is the
file docs/DEPLOY.md tells a site to provision from, so a fresh install would
have failed at `flask plugin apply-profile` with PluginError - the first thing a
receiving site does, broken by the branch meant to serve them. It now names the
twelve that exist, and its comment says the two must agree.

agent/ was never refreshed. Whoever populated this branch copied shopdb/,
plugins/, frontend/ and tests/ from the site line and left the agent tree at its
September state: 22 C# and PowerShell sources missing, including AgentCredentials,
EnrollmentService, AgentHttpFactory and the fleet-alert client, plus one file the
site line had deleted still present. The old tree is internally consistent, so it
compiles, and nothing in CI builds it - every gate was green over a server that
speaks enrollment and per-PC credentials to a bundled agent source that cannot.
Resynced whole.

DECISIONS THIS ENCODES, rather than defers:

- The plugin-authoring lab builds printedparts, whose manifest depends on
  employees, so it could not stay. The lab remains on the site line and main
  ships no build-along tutorial. That is a real loss for an adopting developer
  and is recorded here rather than discovered later.
- Recognition, Training and Recertification notifications are no longer seeded.
  Each splits one notification into a card per employee and renders a photo,
  which needs a plugin this branch does not bundle. Seeding them would offer an
  author a type that cannot resolve anybody. A site that installs employees gets
  them from that plugin's own seed.
- Windows/IIS is documented as the legacy path throughout, and the README leads
  with Docker, because that is what a receiving site gets.

The API description is regenerated for THIS branch - 347 paths and 483
operations, down from 415 and 573 - so the published contract describes what is
here rather than what the site line serves. docs/CONFIG.md lost the two
measuring-tool label keys the code no longer declares, which two lanes had
decided opposite ways.

Suite: 3124 passed, 6 skipped. Naming and style gates pass. The docs gates run
rather than skip, and every index line count is derived from the file it names.

scripts/uninstall-shopdbagent.ps1

@@ -1,10 +1,11 @@
 # uninstall-shopdbagent.ps1
 # ShopDB Endpoint Agent uninstaller. Run from an ELEVATED (admin) PowerShell on
-# the endpoint. Reverses everything install-shopdbagent.ps1 and the site agent
-# generator's install.ps1 create:
+# the endpoint. Reverses everything the site agent generator's install.ps1
+# creates:
 #   - stops and deletes the Windows service
 #   - kills any running agent/tray processes
 #   - removes the tray logon Run key (64-bit and 32-bit views)
+#   - unregisters the ShopDB user-context probe scheduled task
 #   - removes the credential hive HKLM\SOFTWARE\GE\ShopDB (both views)
 #   - removes the Defender path exclusion for the install directory
 #   - deletes the install directory and the ProgramData data/log tree
@@ -20,6 +21,10 @@ param(
 	[string] $ServiceName = "ShopDbEndpointAgent",
 	[string] $TrayExeName = "shopdb-endpoint-tray.exe",
 
+	# Scheduled task that runs the user-context probe in the operator's session.
+	# Must match the installer's -UserContextTaskName.
+	[string] $UserContextTaskName = "ShopDB user-context probe",
+
 	# Also remove any server TLS certificate the site-agent installer imported
 	# into the machine Trusted Root store. Off by default because a root cert is
 	# shared trust material: only pull it when you are sure no other service on
@@ -113,6 +118,34 @@ Start-Sleep -Seconds 1
 # 3. Remove the tray logon Run key entry (both views) and the credential hive.
 Write-Host "[3/6] Removing registry entries ..."
 Remove-HklmBothViews -SubKey "SOFTWARE\Microsoft\Windows\CurrentVersion\Run" -Name "ShopDbEndpointTray"
+
+# Unregister the probe task. Left behind it would keep firing at every logon
+# against a deleted exe, which shows up as a recurring task-failure history on a
+# machine nobody believes has the agent on it any more.
+try {
+	if (Get-ScheduledTask -TaskName $UserContextTaskName -ErrorAction SilentlyContinue) {
+		Unregister-ScheduledTask -TaskName $UserContextTaskName -Confirm:$false -ErrorAction Stop
+		Write-Host "  removed scheduled task '$UserContextTaskName'"
+	}
+	else {
+		Write-Host "  scheduled task '$UserContextTaskName' not present."
+	}
+}
+catch {
+	Write-Warning "  could not remove scheduled task '$UserContextTaskName': $($_.Exception.Message)"
+}
+
+# The install's one-shot tray launcher is transient and normally removes itself,
+# but an install that failed partway can leave it behind.
+try {
+	if (Get-ScheduledTask -TaskName "ShopDB tray first launch" -ErrorAction SilentlyContinue) {
+		Unregister-ScheduledTask -TaskName "ShopDB tray first launch" -Confirm:$false -ErrorAction Stop
+		Write-Host "  removed leftover scheduled task 'ShopDB tray first launch'"
+	}
+}
+catch {
+	Write-Warning "  could not remove scheduled task 'ShopDB tray first launch': $($_.Exception.Message)"
+}
 Remove-HklmBothViews -SubKey "SOFTWARE\GE\ShopDB"
 
 # Remove the All-Users Start Menu shortcut the site-agent installer created.