feat: initial corvid — standalone ticket service extracted from homelab-dashboard

Extracts the ticket/attachment system into a reusable pip-installable package.
Centralises homelab MCP server (tickets, attachments, system logs) here.

- corvid package: models, router (make_router factory), config, standalone main
- Alembic migration chain for fresh standalone deployments
- Docker Compose for standalone deployment (port 8090)
- mcp_server.py: moved from homelab-dashboard, CORVID_REPO_PATH configurable

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

alembic.ini

@@ -0,0 +1,41 @@
+[alembic]
+script_location = alembic
+file_template = %%(version_num)s_%%(slug)s
+prepend_sys_path = .
+version_path_separator = os
+
+sqlalchemy.url =
+
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S