Apply skill-driven review fixes: security, hook isolation, tests, docs

Addresses findings from a 6-lens review against the project skills
(defining-asset-contract, enforcing-plugin-contract, hardening-flask-config,
integrating-plugin-hooks, pinning-flask-behavior, simplifying-python).

Security (hardening-flask-config):
- Load per-plugin COLLECTOR_API_KEY_<PLUGIN> from env in create_app. from_object
  only copies class attributes, so per-plugin keys (ADR-006) were dead in real
  deploys and silently fell back to the shared key.
- EMPLOYEE_DB_USER/PASSWORD no longer default to root/rootpassword (no safe
  default for a secret; unset fails loud). Documented in .env.example + DEPLOY.md.
- COLLECTOR_API_KEY + per-plugin + EMPLOYEE_DB_* added to .env.example/DEPLOY.md.

Hook isolation (integrating-plugin-hooks):
- collector _collector_plugins and dashboard get_navigation now re-raise in
  dev/test and log+isolate in prod, instead of silently swallowing a broken
  plugin hook.

Plugin loader (enforcing-plugin-contract):
- enable_plugin/install_plugin read dependencies+version from the manifest
  instead of instantiating the plugin class.
- _register_plugin_components rejects a second plugin claiming an already-used
  api_prefix (reset per app in init_app).

Tests (pinning-flask-behavior):
- test_identifiers.py: gauge/maintenance round-trip on computer/printer/network
  create+update; per-type seed yields the 12 identifier keys.
- contract tests for apply_collector_payload presence + schema-declarers-implement.
- security tests for per-plugin key env loading + no employee-db password default.

Docs/contract sync (defining-asset-contract):
- PLUGIN-HOOKS.md documents apply_collector_payload; stale 0.2.0 -> 0.3.0.
- ADR-006 documents apply_collector_payload + single-dispatch rationale.
- ADR-001 enumerates the expanded shopdb.api import surface.

Simplify (simplifying-python):
- De-duplicate the 21-entry settings defaults: shared build_default_settings()
  used by both the /settings/seed route and the CLI (were drifting copies).
- Remove dead AssetStatus import + redundant AssetType local import in computers
  plugin; comment the statusid=1 collector default.

153 tests pass (was 145), naming/style green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/adr/ADR-006-collector-contract.md

@@ -15,7 +15,7 @@ This calls for a generalizable contract: any plugin that wants to accept externa
 
 ## Decision
 
-`BasePlugin` gets one new optional hook:
+`BasePlugin` gets two new hooks (added in __contract_version__ 0.2.x -> the surface is carried at 0.3.0):
 
 ```python
 def get_collector_schema(self) -> Optional[dict]:
@@ -29,9 +29,26 @@ def get_collector_schema(self) -> Optional[dict]:
     - 'fields': JSON Schema definitions for the rest of the payload.
     """
     return None
+
+def apply_collector_payload(self, payload: dict) -> dict:
+    """Idempotently upsert an asset from a validated collector payload.
+
+    Called by /api/collector/<pluginname> after identity validation.
+    CONDITIONAL hook: required only when get_collector_schema returns
+    non-None. Default raises NotImplementedError (the dispatcher returns
+    500) so a schema-without-upsert fails loud. Returns a dict with at
+    least 'action' ('created'|'updated'|'noop'), 'assetid', 'warnings'.
+    """
+    raise NotImplementedError
 ```
 
-Plugin loader auto-registers an endpoint at `/api/collector/<pluginname>` for each plugin returning a schema. Auth is API-key, separate from JWT. Per-plugin keys via env vars:
+The pairing (schema present => apply implemented) is enforced by the
+`test_schema_declaring_plugins_implement_apply` contract test.
+
+A single dynamic dispatch route `/api/collector/<pluginname>` serves every
+plugin that returns a schema (rather than registering a blueprint per plugin),
+because Flask forbids `register_blueprint` after the first request and plugins
+can be enabled at runtime. Auth is API-key, separate from JWT. Per-plugin keys via env vars:
 
 - `COLLECTOR_API_KEY_<PLUGINNAME>` (preferred, plugin-specific)
 - `COLLECTOR_API_KEY` (fallback, shared)
@@ -125,7 +142,7 @@ Migration path:
 ## References
 
 - `shopdb/core/api/collector.py` (legacy endpoint to be removed)
-- `shopdb/plugins/base.py` (`get_collector_schema` hook to be added)
+- `shopdb/plugins/base.py` (`get_collector_schema` + `apply_collector_payload` hooks)
 - ADR-001 (asset model the collectors target)
 - ADR-002 (collector schema is part of plugin contract; changes to the hook signature are major bumps)
 - The PXE project (`/home/camp/projects/pxe/`) which feeds the computers collector