feat: integer cents money handling, order page fixes, and vendor filter persistence

Money Handling Architecture:
- Store all monetary values as integer cents (€105.91 = 10591)
- Add app/utils/money.py with Money class and conversion helpers
- Add static/shared/js/money.js for frontend formatting
- Update all database models to use _cents columns (Product, Order, etc.)
- Update CSV processor to convert prices to cents on import
- Add Alembic migration for Float to Integer conversion
- Create .architecture-rules/money.yaml with 7 validation rules
- Add docs/architecture/money-handling.md documentation

Order Details Page Fixes:
- Fix customer name showing 'undefined undefined' - use flat field names
- Fix vendor info empty - add vendor_name/vendor_code to OrderDetailResponse
- Fix shipping address using wrong nested object structure
- Enrich order detail API response with vendor info

Vendor Filter Persistence Fixes:
- Fix orders.js: restoreSavedVendor now sets selectedVendor and filters
- Fix orders.js: init() only loads orders if no saved vendor to restore
- Fix marketplace-letzshop.js: restoreSavedVendor calls selectVendor()
- Fix marketplace-letzshop.js: clearVendorSelection clears TomSelect dropdown
- Align vendor selector placeholder text between pages

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

models/schema/letzshop.py

@@ -31,6 +31,21 @@ class LetzshopCredentialsCreate(BaseModel):
     sync_interval_minutes: int = Field(
         15, ge=5, le=1440, description="Sync interval in minutes (5-1440)"
     )
+    test_mode_enabled: bool = Field(
+        False, description="Test mode - disables API mutations"
+    )
+    default_carrier: str | None = Field(
+        None, description="Default carrier (greco, colissimo, xpresslogistics)"
+    )
+    carrier_greco_label_url: str | None = Field(
+        "https://dispatchweb.fr/Tracky/Home/", description="Greco label URL prefix"
+    )
+    carrier_colissimo_label_url: str | None = Field(
+        None, description="Colissimo label URL prefix"
+    )
+    carrier_xpresslogistics_label_url: str | None = Field(
+        None, description="XpressLogistics label URL prefix"
+    )
 
 
 class LetzshopCredentialsUpdate(BaseModel):
@@ -40,6 +55,11 @@ class LetzshopCredentialsUpdate(BaseModel):
     api_endpoint: str | None = None
     auto_sync_enabled: bool | None = None
     sync_interval_minutes: int | None = Field(None, ge=5, le=1440)
+    test_mode_enabled: bool | None = None
+    default_carrier: str | None = None
+    carrier_greco_label_url: str | None = None
+    carrier_colissimo_label_url: str | None = None
+    carrier_xpresslogistics_label_url: str | None = None
 
 
 class LetzshopCredentialsResponse(BaseModel):
@@ -53,6 +73,11 @@ class LetzshopCredentialsResponse(BaseModel):
     api_endpoint: str
     auto_sync_enabled: bool
     sync_interval_minutes: int
+    test_mode_enabled: bool = False
+    default_carrier: str | None = None
+    carrier_greco_label_url: str | None = None
+    carrier_colissimo_label_url: str | None = None
+    carrier_xpresslogistics_label_url: str | None = None
     last_sync_at: datetime | None
     last_sync_status: str | None
     last_sync_error: str | None
@@ -101,6 +126,7 @@ class LetzshopOrderResponse(BaseModel):
 
     id: int
     vendor_id: int
+    vendor_name: str | None = None  # For cross-vendor views
     order_number: str
 
     # External references