feat(admin): add cache purge controls to settings

Add `purgeMetadataCache` and `purgeImageCache` procedures that let admins free disk space on demand. Metadata purge removes un-enriched stub titles not in any user's library plus orphaned person records; image purge deletes all cached TMDB files from disk.

Expose both as POST endpoints under `/admin/cache/` via the oRPC contract, implement the core logic in a new `@sofa/core/cache` module, and surface them in a new "Danger Zone" section on the Settings page with individual confirmation dialogs and a combined "Purge all" action.

docs/content/docs/api/admin.mdx

@@ -43,6 +43,12 @@ _openapi:
     - depth: 2
       title: Trigger cron job
       url: '#trigger-cron-job'
+    - depth: 2
+      title: Purge metadata cache
+      url: '#purge-metadata-cache'
+    - depth: 2
+      title: Purge image cache
+      url: '#purge-image-cache'
   structuredData:
     headings:
       - content: List backups
@@ -71,6 +77,10 @@ _openapi:
         id: toggle-telemetry
       - content: Trigger cron job
         id: trigger-cron-job
+      - content: Purge metadata cache
+        id: purge-metadata-cache
+      - content: Purge image cache
+        id: purge-image-cache
     contents:
       - content: Fetch all database backups with their sizes and creation times.
         heading: list-backups
@@ -110,8 +120,16 @@ _openapi:
           Manually trigger a background cron job by name. The job runs
           asynchronously.
         heading: trigger-cron-job
+      - content: >-
+          Delete un-enriched stub titles not in any user's library and clean up
+          orphaned person records.
+        heading: purge-metadata-cache
+      - content: >-
+          Delete all cached TMDB images from disk. Images will be re-downloaded
+          on demand.
+        heading: purge-image-cache
 ---
 
 {/* This file was generated by Fumadocs. Do not edit this file directly. Any changes should be made by running the generation command again. */}
 
-<APIPage document={"./openapi.json"} webhooks={[]} operations={[{"path":"/admin/backups","method":"get"},{"path":"/admin/backups","method":"post"},{"path":"/admin/backups/{filename}","method":"delete"},{"path":"/admin/backups/restore","method":"post"},{"path":"/admin/backups/schedule","method":"get"},{"path":"/admin/backups/schedule","method":"put"},{"path":"/admin/registration","method":"get"},{"path":"/admin/registration","method":"put"},{"path":"/admin/update-check","method":"get"},{"path":"/admin/update-check","method":"put"},{"path":"/admin/telemetry","method":"get"},{"path":"/admin/telemetry","method":"put"},{"path":"/admin/jobs/trigger","method":"post"}]} showTitle={true} />
+<APIPage document={"./openapi.json"} webhooks={[]} operations={[{"path":"/admin/backups","method":"get"},{"path":"/admin/backups","method":"post"},{"path":"/admin/backups/{filename}","method":"delete"},{"path":"/admin/backups/restore","method":"post"},{"path":"/admin/backups/schedule","method":"get"},{"path":"/admin/backups/schedule","method":"put"},{"path":"/admin/registration","method":"get"},{"path":"/admin/registration","method":"put"},{"path":"/admin/update-check","method":"get"},{"path":"/admin/update-check","method":"put"},{"path":"/admin/telemetry","method":"get"},{"path":"/admin/telemetry","method":"put"},{"path":"/admin/jobs/trigger","method":"post"},{"path":"/admin/cache/purge-metadata","method":"post"},{"path":"/admin/cache/purge-images","method":"post"}]} showTitle={true} />

docs/openapi.json

@@ -5584,6 +5584,90 @@
         ]
       }
     },
+    "/admin/cache/purge-metadata": {
+      "post": {
+        "operationId": "admin.purgeMetadataCache",
+        "summary": "Purge metadata cache",
+        "description": "Delete un-enriched stub titles not in any user's library and clean up orphaned person records.",
+        "tags": [
+          "Admin"
+        ],
+        "responses": {
+          "200": {
+            "description": "Counts of deleted titles and persons",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "deletedTitles": {
+                      "type": "number",
+                      "description": "Number of un-enriched stub titles deleted"
+                    },
+                    "deletedPersons": {
+                      "type": "number",
+                      "description": "Number of orphaned person records deleted"
+                    }
+                  },
+                  "required": [
+                    "deletedTitles",
+                    "deletedPersons"
+                  ],
+                  "description": "Result of purging un-enriched metadata from the database"
+                }
+              }
+            }
+          }
+        },
+        "security": [
+          {
+            "session": []
+          }
+        ]
+      }
+    },
+    "/admin/cache/purge-images": {
+      "post": {
+        "operationId": "admin.purgeImageCache",
+        "summary": "Purge image cache",
+        "description": "Delete all cached TMDB images from disk. Images will be re-downloaded on demand.",
+        "tags": [
+          "Admin"
+        ],
+        "responses": {
+          "200": {
+            "description": "Count of deleted files and bytes freed",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "deletedFiles": {
+                      "type": "number",
+                      "description": "Number of image files deleted from disk"
+                    },
+                    "freedBytes": {
+                      "type": "number",
+                      "description": "Total bytes freed from disk"
+                    }
+                  },
+                  "required": [
+                    "deletedFiles",
+                    "freedBytes"
+                  ],
+                  "description": "Result of purging the image cache from disk"
+                }
+              }
+            }
+          }
+        },
+        "security": [
+          {
+            "session": []
+          }
+        ]
+      }
+    },
     "/account/name": {
       "put": {
         "operationId": "account.updateName",