Bring the wilm branch into main: endpoints plugin, agent, policies, CSV import

Ports the corporate-GitHub wilm branch onto main, keeping the two branches
separate. Thirteen upstream commits arrive with their authorship intact; the
review fixes and the portability work below are on top.

What arrives:

  endpoints plugin  - a ShopDB agent reporting endpoint state, telemetry,
                      services and interfaces, with a command channel the agent
                      long-polls. Ingest stays on the generic collector route
                      (ADR-006); the agent key is a UI-managed single-scope
                      token whose revocation is an instant kill switch.
  computers policies - Configuration and Business Policies (RMM-style), scope
                      trees validated at write time, actions checked against
                      the endpoints command allowlist. Feature-gated: every
                      route 404s while the setting is off, so enabling it can
                      never half-expose the surface.
  asset CSV import  - templates, a collector script carrying the site path, and
                      a validate-then-commit import. A plugin can own a virtual
                      column plus a post-write row hook, which is how a PC's
                      machine number becomes a controls link without a
                      hand-built relationships sheet.
  agent/            - the Windows agent and its installer.

Contract 0.21.0 -> 0.24.0, additive throughout: register_import_hook (0.22),
mint/list/revoke_service_token (0.23), collector_authorized (0.24). The stability
table had no rows for any of them and now does.

MySQL 5.6 portability. The branch stored three policy columns as sa.JSON, the
only JSON columns in the product, and 5.6 has no JSON type: the migration failed
with a bare syntax error near the word JSON. They are TEXT now, through a
JSONText type decorator, so all seventeen call sites still read and write dicts.
The convention elsewhere is already TEXT (guides.blocksjson,
geenforce.manifestjson).

Review fixes carried on top:

  - six policy GETs were jwt_required(optional=True), which authenticates a
    caller without checking anything; they require computers.view now, and six
    redundant jwt_required decorators are gone
  - the agent installer took a default BaseUrl and CollectorKey, so a mistyped
    run silently pointed an endpoint at the wrong instance; both are mandatory
    and a non-https BaseUrl throws unless -AllowInsecureHttp is passed
  - a committing CSV import wrote no audit row

Documentation: the 34 new routes are described in docs/api-inventory.json, which
is hand-maintained on purpose, and the generated spec now covers 331 paths and
477 operations across 22 surfaces. DEVELOPMENT-SETUP's 1071 troubleshooting row
said "use MySQL 8 for dev" and now gives the actual fix, including the trap that
5.6 downgrades ROW_FORMAT=DYNAMIC to Compact with a warning instead of an error.

Full suite 2123 passed, vitest 260 passed, all seventeen plugin chains migrate
clean on MySQL 5.6 and the naming, docs, parity and read-surface gates are green.

docs/CONTRACT-STABILITY.md

@@ -41,6 +41,9 @@ Recorded in the comment block in `shopdb/__init__.py`:
 | 0.19.0 | **BREAKING.** `get_dashboard_widgets` returns DATA AND SHAPE, not a component name. The old shape (`name` + `component` + `size`) named a Vue component per widget, which cannot survive a lean build - a plugin's component may never be staged into the frontend bundle (ADR-013) - and five plugins were declaring widgets that pointed at components nobody had written. A card now declares `id` / `title` / `endpoint` / `render` / `severity` / `permission` / `empty` / `position`; see PLUGIN-HOOKS.md. Also added `send_upload` so a plugin serving user-supplied bytes gets the headers that keep an SVG from running as script | **contract change (minor, pre-1.0)** |
 | 0.20.0 | The `Asset` model gained `levelid` (which floor plan its `mapx`/`mapy` are pixels of) and `mapverifiedat`; `Location` gained `levelid` too, and `resolve_asset_position` now returns the `levelid` belonging to whichever source supplied the coordinates. A plugin that writes a map position MUST write the level with it - a position without one renders as "level unknown" rather than being drawn on the default drawing, because a marker on the wrong floor plan looks correct (ADR-017) | additive surface (minor) |
 | 0.21.0 | Added the `get_guest_grantable_permissions` hook: a plugin names the WRITE permissions a site may grant to the seeded `guest` role, which is who anyone without a token now holds. Reads (`.view`/`.read`) are grantable without a plugin saying anything; anything else is refused. Also exposed `require_any_permission` on `shopdb.api` for a read two different rights should reach | additive optional hook + surface (minor) |
+| 0.22.0 | Added the `register_import_hook` surface: a plugin owns a VIRTUAL COLUMN on an importable CSV table - a header the bulk importer accepts but never writes - plus a post-write row hook that turns the value into a plugin concept. The computers plugin uses it for `machineassetnumber` on `computers.csv`, which builds the PC->machine controls link, so a site writes the machine number in the PC's own row instead of hand-building a separate relationships sheet. Core never learns what the column means. `RowWarning` is exported with it so a hook can report a soft failure without aborting the import | additive surface (minor) |
+| 0.23.0 | Added `mint_service_token`, `list_service_tokens` and `revoke_service_tokens` so a plugin can provision, list and revoke a single-scope managed service token without importing core token internals. The endpoints plugin uses them for a UI-managed, regenerable agent key scoped to `collector.ingest.endpoints` alone - narrow on purpose, so rotating or revoking it cannot disturb the computers or GE-Enforce collectors, and revocation is an instant kill switch on agent ingest | additive surface (minor) |
+| 0.24.0 | Added `collector_authorized(pluginname)` so a plugin can gate an agent-facing route that lives OUTSIDE the generic collector blueprint on the same per-plugin key and kill switch the ingest route uses. The endpoints command channel needs it: the agent long-polls `/api/endpoints/commands/next` and posts results back, and those are agent callbacks rather than JWT routes. Without it a plugin would reach into core collector internals to authorize them | additive surface (minor) |
 
 The source comment block documents 0.3.0, 0.4.0, 0.6.0, 0.7.0, 0.9.0, 0.10.0,
 0.11.0, 0.16.0, 0.18.0 and 0.19.0; 0.12.0 through 0.15.0 and 0.17.0 are recorded