Docs: guides in the indexes, the stalest-kind rule, and the changelog

Guides was shipped without an entry in PLUGINS.md or START-HERE, so a site
adopting the product had no way to find out it exists.

BACKUP-KINDS.md described a host's badge as coming from the most recently
confirmed kind. It has not worked that way since the fleet report was reworked:
the freshest revision per (host, kind) is taken, and then the STALEST of those
kinds decides, because reporting the freshest would let a healthy NTLARS backup
mask a part-marker capture that stopped a month ago. Stalest among kinds that
can be JUDGED - a kind never confirmed is unmeasurable, not stale, and treating
it as the worst value made a host with a working backup show no badge at all.

The backups row also still advertised UDC and CMM kinds that do not exist.

api-inventory, openapi.json and PROJECT-MAP regenerated.

docs/PLUGINS.md

@@ -22,7 +22,8 @@ These plugins are in `plugins/` in this repo. Enable per site with `flask plugin
 | `slides` | Slides for the lobby display and shop-floor screensaver | Upload / reorder / delete per surface. Management gated on the `slides.manage` permission, grantable to non-admin curators; display routes are public. |
 | `tools` | Technician utilities: barcode and QR label generation, unit conversions, Secure Send | Mostly browser-side by design, so an air-gapped bench gets them with no network. Secure Send is the exception and is why this plugin has a blueprint, a table and a migration chain: see [SECURE-SEND.md](SECURE-SEND.md). |
 | `warranty` | Asset warranty tracking | Manual entry now, Dell / Lenovo / HP provider lookups later. Derived coverage status with report buckets. |
-| `backups` | Per-asset configuration backups with revision history: NTLARS/DNC registry, part marker, UDC, CMM | Kind-pluggable per [BACKUP-KINDS.md](BACKUP-KINDS.md); a kind is one class in `services/registry.py`. Parseable kinds store a JSON projection and re-render to the native format on download; opaque vendor formats stay on the SFLD share with ShopDB holding metadata and the UNC pointer. Fed by the collector, so ingest authorizes on a `collector.ingest` service token, not a user JWT. `backups.view` and `backups.download` are separate permissions because a `.reg` is a restorable artifact. Not to be confused with [BACKUP-RESTORE.md](BACKUP-RESTORE.md), which is the ShopDB database itself. |
+| `guides` | Step-by-step procedures written in ShopDB: typed blocks, pasted screenshots, live checkboxes, tags, drafts and revision history | Content is stored as typed blocks rather than markup, so the same guide renders to screen, dark mode and paper. Readers see the PUBLISHED revision only - a technician following a procedure must not have it change under them mid-task. Checkbox ticks are per-viewer and never edit the guide. See [GUIDES.md](GUIDES.md). |
+| `backups` | Per-asset configuration backups with revision history: NTLARS/DNC registry and part marker | Kind-pluggable per [BACKUP-KINDS.md](BACKUP-KINDS.md); a kind is one class in `services/registry.py`. Parseable kinds store a JSON projection and re-render to the native format on download; opaque vendor formats stay on the SFLD share with ShopDB holding metadata and the UNC pointer. Fed by the collector, so ingest authorizes on a `collector.ingest` service token, not a user JWT. `backups.view` and `backups.download` are separate permissions because a `.reg` is a restorable artifact. Not to be confused with [BACKUP-RESTORE.md](BACKUP-RESTORE.md), which is the ShopDB database itself. |
 
 ## Plugin permissions