feat: add listing edit mode with owner detection, fix service worker API caching for external domain

docs/DIRECTUS-SCHEMA.md

@@ -193,7 +193,7 @@ Meldungen von Anzeigen.
 
 | Collection | Read | Create | Update | Delete | Hinweise |
 |------------|:----:|:------:|:------:|:------:|----------|
-| `listings` | ✓ | ✓ | ✓* | - | Nur `status=published` lesen, *Update nur `views` (via Flow) |
+| `listings` | ✓ | ✓ | ✓ | - | Siehe Details unten |
 | `listings_files` | ✓ | ✓ | - | - | Für Bilder-Upload |
 | `directus_files` | ✓ | ✓ | - | - | Asset-Upload |
 | `categories` | ✓ | - | - | - | Nur `status=published` |
@@ -205,6 +205,27 @@ Meldungen von Anzeigen.
 | `favorites` | ✓ | ✓ | - | ✓ | Nur eigene |
 | `reports` | - | ✓ | - | - | Nur erstellen |
 
+### Listings Update-Berechtigungen (Detail)
+
+**Custom Filter:**
+```json
+{ "user_created": { "_eq": "$CURRENT_USER" } }
+```
+
+**Field Permissions (Update):**
+- `title`, `slug`, `description`
+- `price`, `currency`, `price_mode`, `price_type`
+- `category`, `condition`, `location`
+- `shipping`, `shipping_cost`
+- `monero_address`
+- `images`
+- `views` (geschützt durch Flow)
+
+**Read Filter:**
+```json
+{ "status": { "_eq": "published" } }
+```
+
 ---
 
 ## Directus Flows