Phase 6: simplify-pass policy, plugins listing, roadmap to 1.0

End-of-pipeline cleanup. No structural changes; documents what is
done, what is left, and the discipline for future cleanup commits.

Skill:
- simplifying-python: end-of-session cleanup discipline. Inspired by
  Anthropic's open-sourced code-simplifier. Targets duplication, dead
  code, voodoo constants, stale comments, misnamed identifiers,
  unnecessary abstraction. Anti-targets: architecture, public API
  surface, schema, sweeping rewrites. Behavior preservation enforced
  by running pytest before and after.

Simplify pass on shopdb/utils/responses.py:
- error_response docstring claimed the error info lives at top level
  `error`. Implementation puts it under `data.error` (consistent with
  the success envelope). Implementation is correct; docstring updated.
- paginated_response docstring used snake_case keys (`per_page`,
  `total_pages`, etc). Implementation uses lowercase concatenated per
  CONTRIBUTING.md. Docstring updated to match.

Documentation:
- docs/PLUGINS.md: bundled plugins (six, with what they track and
  caveats per ADR), planned plugins (measuringtools as the scaffold
  canary per ADR-005), distribution conventions for sister-site
  plugins per ADR-003, naming policy.
- docs/ROADMAP.md: phase status table (0-5 done, 6 in progress),
  must-have work for 1.0 (Asset.mapx/mapy, equipment migration,
  printers retirement, frontend hook contract, per-plugin Alembic
  chains), nice-to-have (measuringtools plugin, frontend scaffolding,
  marketplace listing, surface-diff tooling), deferred (multi-tenancy,
  pip-installable plugins, event bus). Defines what 1.0.0 means as a
  contract.

Test count unchanged: 101 passing. Naming/style check green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/PLUGINS.md

@@ -0,0 +1,47 @@
+# Plugins
+
+shopdb-flask is a framework. The plugins listed here are the pieces other GE Aerospace facilities can install, build, or skip per ADR-003. Bundled plugins ship in the framework repo. External plugins live in their own repos and drop into `<repo>/plugins/<name>/` at install time.
+
+## Bundled (ship with the framework)
+
+These six plugins are in `plugins/` in this repo. Enable per site with `flask plugin install <name>`.
+
+| Plugin | Tracks | Notes |
+|--------|--------|-------|
+| `equipment` | Manufacturing machinery: 5-axis mills, lathes, broachers, heat treatment ovens | Manually entered. See [ADR-005](adr/ADR-005-equipment-vs-measuringtools.md). Subtype tables for FOCAS / CLM / MTConnect controller protocols (planned). |
+| `computers` | Shop-floor PCs and engineering workstations | Fed by the PXE pipeline collector per [ADR-006](adr/ADR-006-collector-contract.md). |
+| `printers` | Network and shop-floor printers | Optional Zabbix integration for supply tracking. Legacy `PrinterData` retiring per ADR-001. |
+| `network` | Switches, routers, access points, IDFs as locations | Asset-only; cleanest of the bundled set. |
+| `usb` | USB devices issued to shop-floor users | Lightweight checkout / check-in. |
+| `notifications` | Shop-floor notifications, recognitions, kiosk feed | Used by `ShopfloorDashboard.vue`. |
+
+## Planned (in the roadmap, not yet built)
+
+| Plugin | Tracks | Status |
+|--------|--------|--------|
+| `measuringtools` | Metrology and inspection: CMMs, Keyence vision, surface profilometers, GenSpec | Per [ADR-005](adr/ADR-005-equipment-vs-measuringtools.md). First plugin to be built using `flask plugin new` as the canary for the scaffold. |
+
+## Building your own
+
+See [PLUGIN-QUICKSTART.md](PLUGIN-QUICKSTART.md) for the 30-minute walkthrough. The contract is locked in [ADR-001](adr/ADR-001-asset-as-platform-contract.md) and versioned per [ADR-002](adr/ADR-002-plugin-versioning.md).
+
+Quick path:
+
+```bash
+flask plugin new cameras --description "Tracks shop-floor surveillance cameras"
+# edit plugins/cameras/models/cameras.py with your fields
+flask plugin install cameras
+```
+
+## Distribution conventions
+
+For sister-site plugins (per [ADR-003](adr/ADR-003-plugin-distribution.md)):
+
+- Plugin lives in its own git repo: `gitea.proudtech.net/<your-site>/<pluginname>`
+- Adopting site clones or symlinks into their `<repo>/plugins/<name>/`
+- Plugin manifest declares `core_version` range matching the framework version they target
+- Plugin readme explains: what it tracks, who maintains it, where to file issues
+
+## Naming policy
+
+Plugin names follow the framework's naming convention (lowercase concatenated, no underscores or dashes; full words preferred over acronyms). See [CONTRIBUTING.md](../CONTRIBUTING.md). Plugin name collisions across sites are not enforced; the convention recommends prefixing site-specific plugins with the site code (e.g., `wjsf-shippingstation`) when there is risk of overlap.