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.

.github/workflows/scan-darkwing-pr.yml

@@ -1,62 +0,0 @@
-# Darkwing scan on pull requests, so the "check against darkwing" is a check
-# and not a thing somebody remembers to click.
-#
-# WHY THIS IS SEPARATE from scan-darkwing-portable.yml: that file is copied
-# byte-for-byte from the ge-aero/darkwing README and is left alone so it keeps
-# matching the sanctioned integration. Everything below is ours.
-#
-# THE TRAP THIS AVOIDS. The README workflow resolves its scan target as
-# `inputs.target_ref || 'main'`. On a pull_request event there are no inputs,
-# so that expression falls through to 'main' and the job scans the default
-# branch instead of the code under review - a green Darkwing check that never
-# looked at the change. Resolve the head SHA explicitly.
-#
-# Darkwing exits 0 whatever it finds (its own FAQ: "Does a finding fail my
-# build? No."), so a passing job means the scan RAN, not that the code is
-# clean. Findings land in Security -> Code scanning. Turning a finding into a
-# hard failure means reading findings.sarif ourselves; the commented step at
-# the bottom is the shape of that, deliberately left off until we have seen the
-# false-positive rate on this repo.
-name: Scan (darkwing, PR)
-
-on:
-  pull_request:
-
-permissions:
-  contents: read
-  security-events: write
-  actions: read
-
-# One scan per PR. A new push supersedes the old one rather than queueing a
-# second Bedrock spend against a diff nobody is reviewing any more.
-concurrency:
-  group: darkwing-pr-${{ github.ref }}
-  cancel-in-progress: true
-
-jobs:
-  scan:
-    runs-on: darkwing-scan
-    steps:
-      - uses: ge-aero/darkwing@v1
-        with:
-          # The PR's head, NOT the default branch. See the note above.
-          target_ref: ${{ github.event.pull_request.head.sha }}
-
-      # Gating, once the signal is trusted. Darkwing writes findings.sarif into
-      # its work dir and attaches it as the `findings` artifact; this reads the
-      # severities out and fails on error-level results only.
-      #
-      # - name: Fail on error-level findings
-      #   run: |
-      #     python - <<'PY'
-      #     import json, pathlib, sys
-      #     sarif = pathlib.Path('darkwing/findings.sarif')
-      #     if not sarif.is_file():
-      #         sys.exit('no findings.sarif: the scan did not produce results')
-      #     doc = json.loads(sarif.read_text())
-      #     bad = [r for run in doc.get('runs', [])
-      #              for r in run.get('results', [])
-      #              if r.get('level') == 'error']
-      #     if bad:
-      #         sys.exit(f'{len(bad)} error-level finding(s); see the Security tab')
-      #     PY