Make the server authoritative for what endpoints watch and launch

Fleet health showed dncMain.exe red on endpoints that never ran eDNC. Three
layers each re-added the monitor, so fixing any one of them in isolation left
the others to put it back.

The installer baked a watch list into appsettings.json on every package, and
appsettings.json is never rewritten on the box, so an entry outlived whatever
policy justified it. The server auto-attached shipped monitors by PC type name.
The agent then UNIONED the server's resolved list with its local one, so an
entry could never be removed from the server side at all.

Now: the installer seeds nothing, auto-attach by PC type is gone, and
MonitorConfig.Merge replaces the local list with the server's. Null and empty
stay distinct - null means the fetch failed so keep what we have, empty means
watch nothing. Collapsing those blanks monitoring fleet-wide on one failed HTTP
call, or makes detaching the last monitor silently do nothing forever.

Ingest filters reported services against the resolved monitors as well. The
agent config sits on the endpoint, so it is not a trustworthy account of what
that endpoint should be reporting.

Launch paths move the same way, which exposed an older bug. MTConnect installs
to ProgramData and starts through run.bat, but LaunchPathPolicy approved only
the Program Files roots, so the launchpath on its shipped monitor row - seeded
in 0006, present from the start - was rejected every time as outside every
approved root. That was invisible because a local launchpaths entry wins in
ResolveLaunchPath and never reaches validation; remote start worked only
through the bypass. The same precedence meant editing an eDNC, UDC or MTConnect
path in the WebUI could never reach an existing endpoint.

So ProgramData is approved and the local launch map ships empty. ProgramData is
world-writable and the agent launches as SYSTEM, which is why it was excluded
originally; it is deliberately too broad for now and carries a REVISIT comment.
The remaining gates still hold - admin-configured monitor row, exists,
launchable extension, re-checked after symlink resolution. Narrowing it to
ProgramData\udc needs the fleet's non-Program-Files install locations
confirmed first.

Also seeds the Office ProPlus LTSC monitor templates, x64 and x86 as separate
rows since they differ only by path, and adds an agent test project. It links
the platform-pure sources rather than referencing the net8.0-windows assembly
so the semantics run on the Linux CI runners. Writing those tests caught a
merge bug where only the dedupe key was trimmed and the stored name was not.

Note for the wj merge: plugins/usb/frontend/views/usbSettings.spec.js fails on
this branch and is untouched here. Commit da91a29 added four kiosk settings the
save assertion does not expect. The spec looks like the stale side, but that is
the usb author's call - flagging rather than guessing.

plugins/endpoints/api/monitors.py

@@ -28,22 +28,13 @@ from ..models import EndpointMonitor
 from .routes import endpoints_bp
 
 
-# Which PC type the shipped monitors attach to, as a SETTING rather than a
-# literal (ADR-015). PC-type vocabulary is per-site seed data: a plant whose
-# type is called "Shop Floor Workstation" got no shipped monitors at all when
-# this was hardcoded, and a plant that happens to use the name for something
-# else got all of them. The default matches the seeded type so nothing changes
-# for a site that uses it; a blank setting attaches the shipped bundle to
-# nothing, which is the right neutral behaviour for a site that does not want
-# it rather than a silent mismatch.
+# RETIRED. This setting named the PC type the shipped monitors auto-attached
+# to, defaulting to 'Shopfloor PC'. That auto-attach path is gone - policy is
+# now the only attachment route (see _resolve_pctype_monitors) - so nothing
+# reads this. The key is kept named here, not deleted, so an existing row in a
+# site's settings table is recognisable as dead rather than mysterious, and so
+# the key is not reused for something else later.
 SHIPPED_PCTYPE_SETTING = 'plugin.endpoints.shippedmonitorpctype'
-SHIPPED_DEFAULT_PCTYPE = 'Shopfloor PC'
-
-
-def shipped_pctype():
-    """The PC type the shipped monitor bundle attaches to at this site."""
-    configured = Setting.get(SHIPPED_PCTYPE_SETTING, default=SHIPPED_DEFAULT_PCTYPE)
-    return (configured or '').strip()
 
 _VALID_KINDS = ('process', 'service')
 
@@ -170,20 +161,25 @@ def delete_monitor(monitor_id):
 
 
 def _resolve_pctype_monitors(pctype):
-    """Monitor definitions a PC type should watch: shipped defaults + policy.
+    """Monitor definitions a PC type should watch, from site policy alone.
+
+    Policy is the ONLY attachment route. Shipped monitors used to also attach
+    automatically to whichever PC type the shipped-pctype setting named, which
+    defaulted to 'Shopfloor PC' - so eDNC, UDC and MTConnect were expected
+    monitors on every endpoint of that type at every site, with no policy
+    anywhere and no way to see why. 0019 split the shipped bundle into
+    per-monitor policies and removed the shipped SITE policy, intending
+    "off by default"; this branch survived and kept them attached, which is
+    why dncMain.exe kept appearing in Fleet health for all endpoints.
+
+    Shipped monitors still exist and are still editable - a site composes them
+    through a Site Policy like anything else. What no longer happens is
+    attaching them because a PC type happens to carry a particular name.
 
-    Shipped monitors attach to the PC type named by the shipped-pctype setting;
-    policy-attached monitors come from the computers policy resolver by PC type.
     Returns a list of EndpointMonitor rows (active only), de-duped by id.
     """
     selected = {}
 
-    shipped_for = shipped_pctype()
-    if shipped_for and pctype == shipped_for:
-        for monitor in EndpointMonitor.query.filter_by(
-                source='shipped', isactive=True).all():
-            selected[monitor.endpointmonitorid] = monitor
-
     computertypeid = _computertypeid_for(pctype)
     if computertypeid is not None:
         policy_ids = _policy_monitor_ids(computertypeid)