Phase 0 Complete: Tasks 0.7-0.20

- 0.7: UI-Design-Richtlinien (docs/ui-design-guidelines.md, 535 lines)
- 0.8: Theme-Customization Backend (4 theme fields, migration 0023)
- 0.9: Theme-Customization Frontend (SettingsTheme.tsx, themeStore.ts, live preview)
- 0.10: RBAC-Audit (4 plugins secured, 53 routes with require_permission)
- 0.11: LiteLLM-Cleanup (llm_client.py migrated from httpx to litellm)
- 0.12: KI-Agent-Framework docs (plugin-development-guide.md, agent_capabilities field)
- 0.13: Heartbeat configurable (ProactiveSettings, migration 0024, frontend UI)
- 0.14: Unified Search Field-Level RBAC (resolve_permissions + filter_fields_by_permission)
- 0.15: Undo/History-System (EntityHistory model, service, routes, migration 0025, HistoryViewer)
- 0.16: Storage Backend (LocalStorage + S3Storage, DMS/attachments/mail updated)
- 0.17: Import/Export unified Contact fields (firstname, surname, email_1, phone_1)
- 0.18: .gitignore & Config-Cleanup (webui→frontend, python-jose removed, .env untracked)
- 0.19: Mail-Salt Security-Fix (per-account random salt, migration 0026)
- 0.20: AGPL replaced (PyMuPDF→pypdf, OnlyOffice→Collabora, LICENSE + THIRD_PARTY_LICENSES.md)

alembic/versions/0026_mail_salt_security.py

@@ -0,0 +1,24 @@
+"""Mail salt security fix — add password_salt column to mail_accounts.
+
+Revision ID: 0026
+Revises: 0025_entity_history
+Create Date: 2026-07-23
+
+Existing accounts get an empty salt and will use the legacy hardcoded salt
+for backward compatibility. New accounts and password changes will use
+per-account random salts.
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "0026_mail_salt_security"
+down_revision = "0025_entity_history"
+
+
+def upgrade():
+    op.add_column("mail_accounts", sa.Column("password_salt", sa.String(64), nullable=False, server_default=""))
+
+
+def downgrade():
+    op.drop_column("mail_accounts", "password_salt")