[AZ-513] [AZ-196] [AZ-183] Add /classes CRUD, /devices, fleet OTA

AZ-513: POST/PATCH/DELETE /classes for detection-class CRUD; new
DetectionClass entity, schema, DTOs, IDetectionClassService. Unblocks
ui/AZ-512.

AZ-196: POST /devices auto-assigns sequential azj-NNNN serial+email
+password and inserts a CompanionPC user. Returns plaintext credentials
for the provisioning script.

AZ-183: Resources table + POST /get-update + POST /resources/publish
for fleet OTA. Per-resource encryption_key column AES-256-CBC encrypted
at rest with ResourcesConfig.EncryptionMasterKey; ICache wraps the
per-(arch,stage) latest-versions lookup and is invalidated on publish.

Adds IDbFactory.RunAdmin<T> overload for write-and-return.

Backfills _docs/02_document/module-layout.md to satisfy the implement
skill's File Ownership prerequisite (the _docs/ artifact set predates
the Step 1.5 module-layout addition).

Code review: PASS_WITH_WARNINGS — see
_docs/03_implementation/reviews/batch_05_review.md.

Co-authored-by: Cursor <cursoragent@cursor.com>

_docs/_autodev_state.md

@@ -6,8 +6,9 @@ step: 10
 name: Implement
 status: in_progress
 sub_step:
-  phase: 0
-  name: awaiting-invocation
-  detail: ""
+  phase: 6
+  name: implement-tasks-sequentially
+  detail: "batch 1 / step 9 — code-review"
 retry_count: 0
 cycle: 1
+tracker: jira