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.

shopdb/plugins/cli.py

@@ -903,9 +903,10 @@ def prune_schema(yes: bool, force: bool):
     Schema-lean per-site DBs: the shared core Alembic baseline creates every
     plugin's tables, so a lean site that omits a plugin still carries that
     plugin's (empty) tables. This drops the tables of every plugin in
-    PLUGIN_TABLE_OWNERS that is not installed here, leaving core + chosen-plugin
-    tables only. Run once at deploy AFTER `flask db upgrade` and
-    `flask plugin upgrade-all`.
+    PLUGIN_TABLE_OWNERS that is not installed here, plus the
+    ORPHAN_TABLE_OWNERS tables the core chain creates for no bundled plugin at
+    all, leaving core + chosen-plugin tables only. Run once at deploy AFTER
+    `flask db upgrade` and `flask plugin upgrade-all`.
 
     Dry-run by default; pass --yes to execute. Drops by table name (no plugin
     code import) so it works on a lean image where the omitted plugin's
@@ -915,7 +916,8 @@ def prune_schema(yes: bool, force: bool):
     from sqlalchemy import create_engine, inspect, text
 
     from shopdb.extensions import db
-    from shopdb.plugins.alembic_template import PLUGIN_TABLE_OWNERS
+    from shopdb.plugins.alembic_template import (
+        ORPHAN_TABLE_OWNERS, PLUGIN_TABLE_OWNERS)
 
     pm = current_app.extensions.get('plugin_manager')
     if not pm:
@@ -928,8 +930,15 @@ def prune_schema(yes: bool, force: bool):
 
     # A table is a prune candidate when its owning plugin is not installed here
     # AND the table actually exists in this database.
+    #
+    # ORPHAN_TABLE_OWNERS is folded in here and nowhere else: those tables have
+    # no plugin left to install, so they are never in `installed` and are always
+    # candidates. Without them a lean site carries them for ever, because the
+    # core chain that creates them cannot be edited.
+    candidates = dict(PLUGIN_TABLE_OWNERS)
+    candidates.update(ORPHAN_TABLE_OWNERS)
     victims = []
-    for plugin, tables in PLUGIN_TABLE_OWNERS.items():
+    for plugin, tables in candidates.items():
         if plugin in installed:
             continue
         for tablename in tables: