fix: merge main (v0.161.0) into classification feature branch

Resolve all 40 merge conflicts from merging origin/main into the
classification feature branch. Key resolutions:

- Auto-generated files (BUILD_DATE, VERSION, etc.): use main's version
- API tokens: take main's version (token expiry, reactivation, hard-delete)
- Auth: take main's Dropbox credential sharing + token expiry checking
- Config: take main's social_auth_dropbox_use_global_credentials option
- Files API: take main's improved duplicate handling + rate limiting
- Models: keep ClassificationRuleModel alongside main's new models
- Mobile: take main's mature implementation
- Templates/translations: take main's versions (device deletion, reactivation keys)
- Migration: renumber 038_add_classification_rules → 039_add_classification_rules
  to chain after main's 038_add_api_token_expires_at
- Requirements: take main's version (adds segno QR library)
- Tests: take main's more complete token tests, keep classification imports

migrations/versions/038_add_api_token_expires_at.py

@@ -0,0 +1,43 @@
+"""Add expires_at column to api_tokens table.
+
+Allows API tokens to be issued with an optional lifetime.  If ``expires_at``
+is set, the token is automatically rejected after that timestamp.
+
+Revision ID: 038_add_api_token_expires_at
+Revises: 037_add_user_sessions_and_qr_challenges
+Create Date: 2026-03-18
+"""
+
+from typing import Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "038_add_api_token_expires_at"
+down_revision: Union[str, None] = "037_add_user_sessions_and_qr_challenges"
+depends_on: Union[str, None] = None
+
+
+def upgrade() -> None:
+    """Add expires_at column to api_tokens (idempotent)."""
+    conn = op.get_bind()
+    inspector = sa.inspect(conn)
+    if "api_tokens" not in inspector.get_table_names():
+        return
+    existing_columns = {col["name"] for col in inspector.get_columns("api_tokens")}
+    if "expires_at" not in existing_columns:
+        op.add_column(
+            "api_tokens",
+            sa.Column("expires_at", sa.DateTime(timezone=True), nullable=True),
+        )
+
+
+def downgrade() -> None:
+    """Remove expires_at column from api_tokens."""
+    conn = op.get_bind()
+    inspector = sa.inspect(conn)
+    if "api_tokens" not in inspector.get_table_names():
+        return
+    existing_columns = {col["name"] for col in inspector.get_columns("api_tokens")}
+    if "expires_at" in existing_columns:
+        op.drop_column("api_tokens", "expires_at")

migrations/versions/039_add_classification_rules.py

@@ -1,7 +1,7 @@
 """Add classification_rules table for custom document classification rules.
 
-Revision ID: 038_add_classification_rules
-Revises: 037_add_user_sessions_and_qr_challenges
+Revision ID: 039_add_classification_rules
+Revises: 038_add_api_token_expires_at
 Create Date: 2026-03-17
 """
 
@@ -10,8 +10,8 @@ from typing import Union
 import sqlalchemy as sa
 from alembic import op
 
-revision: str = "038_add_classification_rules"
-down_revision: Union[str, None] = "037_add_user_sessions_and_qr_challenges"
+revision: str = "039_add_classification_rules"
+down_revision: Union[str, None] = "038_add_api_token_expires_at"
 depends_on: Union[str, None] = None