Account export / restore-into-new-tree / delete

New account_service + endpoints under /users/me:
- GET /me/export — zip of every owned tree (account.json + media blobs).
- POST /me/import — restore a backup into NEW trees (ids remapped, media
  re-uploaded); non-destructive, never touches existing data.
- DELETE /me — soft-delete the user, their owned trees, and revoke sessions;
  guarded by retyping the account email.

Settings page wires all three (export download, restore upload, delete with
typed-email confirmation). No migration — uses existing tables + soft-delete.

52 backend tests pass (export→restore round-trip + delete guards); frontend builds.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/openapi.json

@@ -312,6 +312,39 @@
             }
           }
         }
+      },
+      "delete": {
+        "tags": [
+          "users"
+        ],
+        "summary": "Delete Account",
+        "description": "Delete the account: the user, their owned trees, and their sessions.\nRequires retyping the account email as a guard.",
+        "operationId": "delete_account_api_v1_users_me_delete",
+        "requestBody": {
+          "content": {
+            "application/x-www-form-urlencoded": {
+              "schema": {
+                "$ref": "#/components/schemas/Body_delete_account_api_v1_users_me_delete"
+              }
+            }
+          },
+          "required": true
+        },
+        "responses": {
+          "204": {
+            "description": "Successful Response"
+          },
+          "422": {
+            "description": "Validation Error",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/HTTPValidationError"
+                }
+              }
+            }
+          }
+        }
       }
     },
     "/api/v1/users/me/self-person": {
@@ -356,6 +389,70 @@
         }
       }
     },
+    "/api/v1/users/me/export": {
+      "get": {
+        "tags": [
+          "users"
+        ],
+        "summary": "Export Account",
+        "description": "Download a full backup (JSON + media) of every tree the user owns.",
+        "operationId": "export_account_api_v1_users_me_export_get",
+        "responses": {
+          "200": {
+            "description": "Successful Response",
+            "content": {
+              "application/json": {
+                "schema": {}
+              }
+            }
+          }
+        }
+      }
+    },
+    "/api/v1/users/me/import": {
+      "post": {
+        "tags": [
+          "users"
+        ],
+        "summary": "Import Account",
+        "description": "Restore a previously-exported backup into new trees (non-destructive).",
+        "operationId": "import_account_api_v1_users_me_import_post",
+        "requestBody": {
+          "content": {
+            "multipart/form-data": {
+              "schema": {
+                "$ref": "#/components/schemas/Body_import_account_api_v1_users_me_import_post"
+              }
+            }
+          },
+          "required": true
+        },
+        "responses": {
+          "200": {
+            "description": "Successful Response",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "additionalProperties": true,
+                  "type": "object",
+                  "title": "Response Import Account Api V1 Users Me Import Post"
+                }
+              }
+            }
+          },
+          "422": {
+            "description": "Validation Error",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/HTTPValidationError"
+                }
+              }
+            }
+          }
+        }
+      }
+    },
     "/api/v1/trees": {
       "post": {
         "tags": [
@@ -2608,6 +2705,33 @@
   },
   "components": {
     "schemas": {
+      "Body_delete_account_api_v1_users_me_delete": {
+        "properties": {
+          "confirm_email": {
+            "type": "string",
+            "title": "Confirm Email"
+          }
+        },
+        "type": "object",
+        "required": [
+          "confirm_email"
+        ],
+        "title": "Body_delete_account_api_v1_users_me_delete"
+      },
+      "Body_import_account_api_v1_users_me_import_post": {
+        "properties": {
+          "file": {
+            "type": "string",
+            "contentMediaType": "application/octet-stream",
+            "title": "File"
+          }
+        },
+        "type": "object",
+        "required": [
+          "file"
+        ],
+        "title": "Body_import_account_api_v1_users_me_import_post"
+      },
       "Body_import_gedcom_api_v1_trees__tree_id__gedcom_import_post": {
         "properties": {
           "file": {