docs: fix stale migration and endpoint counts, add missing endpoints

- Update migration count from 11 to 13 across all docs (012_bom_source,
  013_move_cost_sourcing_to_props)
- Update endpoint count from 75 to 78 across all docs
- Add 3 missing endpoints to SPECIFICATION.md section 11.1:
  GET /api/events (SSE), GET /api/items/by-uuid/{uuid},
  POST /api/items/{pn}/bom/merge
- Add migrations 012 and 013 to STATUS.md table
- Fix migration 010 description (sourcing_link and standard_cost moved
  to revision properties in 013)

docs/SPECIFICATION.md

@@ -37,7 +37,7 @@ Silo treats **part numbering schemas as configuration, not code**. Multiple numb
                               ▼
 ┌─────────────────────────────────────────────────────────────┐
 │                   Silo Server (silod)                        │
-│  - REST API (75 endpoints)                                  │
+│  - REST API (78 endpoints)                                  │
 │  - Authentication (local, LDAP, OIDC)                       │
 │  - Schema parsing and validation                            │
 │  - Part number generation engine                            │
@@ -598,7 +598,7 @@ See [AUTH.md](AUTH.md) for full architecture details and [AUTH_USER_GUIDE.md](AU
 
 ## 11. API Design
 
-### 11.1 REST Endpoints (75 Implemented)
+### 11.1 REST Endpoints (78 Implemented)
 
 ```
 # Health (no auth)
@@ -615,6 +615,9 @@ GET    /auth/callback                                       # OIDC callback
 # Public API (no auth required)
 GET    /api/auth/config                                     # Auth backend configuration (for login UI)
 
+# Server-Sent Events (require auth)
+GET    /api/events                                          # SSE stream for real-time updates
+
 # Auth API (require auth)
 GET    /api/auth/me                                         # Current authenticated user
 GET    /api/auth/tokens                                     # List user's API tokens
@@ -644,6 +647,7 @@ DELETE /api/projects/{code}                                 # Delete project [ed
 # Items (read: viewer, write: editor)
 GET    /api/items                                           # List/filter items
 GET    /api/items/search                                    # Fuzzy search
+GET    /api/items/by-uuid/{uuid}                            # Get item by UUID
 GET    /api/items/export.csv                                # Export items to CSV
 GET    /api/items/template.csv                              # CSV import template
 GET    /api/items/export.ods                                # Export items to ODS
@@ -689,6 +693,7 @@ GET    /api/items/{partNumber}/bom/export.csv               # Export BOM as CSV
 GET    /api/items/{partNumber}/bom/export.ods               # Export BOM as ODS
 POST   /api/items/{partNumber}/bom                          # Add BOM entry [editor]
 POST   /api/items/{partNumber}/bom/import                   # Import BOM from CSV [editor]
+POST   /api/items/{partNumber}/bom/merge                    # Merge BOM from ODS with conflict resolution [editor]
 PUT    /api/items/{partNumber}/bom/{childPartNumber}        # Update BOM entry [editor]
 DELETE /api/items/{partNumber}/bom/{childPartNumber}        # Remove BOM entry [editor]
 
@@ -734,11 +739,11 @@ POST   /api/inventory/{partNumber}/move
 
 ### 12.1 Implemented
 
-- [x] PostgreSQL database schema (11 migrations)
+- [x] PostgreSQL database schema (13 migrations)
 - [x] YAML schema parser for part numbering
 - [x] Part number generation engine
 - [x] CLI tool (`cmd/silo`)
-- [x] API server (`cmd/silod`) with 75 endpoints
+- [x] API server (`cmd/silod`) with 78 endpoints
 - [x] MinIO integration for file storage with versioning
 - [x] BOM relationships (component, alternate, reference)
 - [x] Multi-level BOM (recursive expansion with configurable depth)