build: 打通 FastAPI 与 Vue 最小工程、依赖与数据库连接

后端入口、配置、Redis 与 Alembic 迁移就位；前端 Vite 工程可安装可构建。

backend/alembic/versions/normalise_upload_prefix_001.py

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+"""
+Copyright 2024-2026 ChatterMate
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+"""prefix stored local upload paths with the static mount
+
+Revision ID: normalise_upload_prefix_001
+Revises: repair_agent_role_seed_001
+Create Date: 2026-08-08
+
+The app had two conventions for a stored local upload. store_upload wrote
+`/api/v1/uploads/...`, matching the static mount; agent photos and profile
+pictures wrote a bare `/uploads/...`. The frontend resolves stored paths
+against the API origin, so the bare ones came out as `https://host/uploads/...`
+and 404'd — every agent avatar and teammate avatar was broken on a self-hosted
+install using local file storage. (S3 deployments were unaffected: those store
+absolute URLs, which pass through untouched.)
+
+The writers now emit the prefix. This brings the existing rows over.
+
+Only values starting exactly with `/uploads/` are touched, so absolute S3 URLs,
+data URIs and already-prefixed rows are left alone and re-running is a no-op.
+
+`/api/v1` is written literally rather than read from settings.API_V1_STR: the
+static mount in main.py hardcodes it too, and a migration should not change
+shape with runtime config.
+"""
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = 'normalise_upload_prefix_001'
+down_revision = 'repair_agent_role_seed_001'
+branch_labels = None
+depends_on = None
+
+# (table, column) pairs that hold a stored upload path written by the
+# bare-/uploads/ writers.
+_COLUMNS = [
+    ('agent_customizations', 'photo_url'),
+    ('users', 'profile_pic'),
+]
+
+
+def upgrade() -> None:
+    for table, column in _COLUMNS:
+        op.execute(
+            f"""
+            UPDATE {table}
+               SET {column} = '/api/v1' || {column}
+             WHERE {column} LIKE '/uploads/%'
+            """
+        )
+
+
+def downgrade() -> None:
+    """Strips the prefix off every local path in these two columns, including
+    rows this migration did not create. That is deliberate: the reverted code
+    writes bare paths and reads them the same way, so the column should end up
+    wholly on the old convention rather than half on each."""
+    for table, column in _COLUMNS:
+        op.execute(
+            f"""
+            UPDATE {table}
+               SET {column} = substring({column} from length('/api/v1') + 1)
+             WHERE {column} LIKE '/api/v1/uploads/%'
+            """
+        )