0.53.0

Changed — may break callers

• drive runs on cli-core's shared program, with its mcp, doctor and skill commands, as gcal, zoom and the
  messengers do (cli-base#390). The command tree, help, failures and run records now come from cli-core 0.501.0.
• mcp serve --tools is gone. drive <profile> commands --json lists every command with its availability for
  the profile, and drive <profile> mcp check starts the server once and counts the tools it offers. mcp gains
  config, add and check; mcp serve keeps --profiles, --permission, --http, --port and --public-url.
• Browser logins of mcp serve --http are kept in a new place (<state>/mcp-http/<profile>.json), so a browser
  app logs in again once. Stop a server started with mcp server start before upgrading: the new mcp server stop
  does not find it.
• doctor --json says oauth_client where it said oauth_application, lists profiles as names, and drops
  login; each profile's selected folders and sign-in storage are in drive session list.
• Failures and parse errors are cli-core's: --profile is refused as an unknown option, an unknown command says
  validation_error with Commander's suggestion, and an expired sign-in no longer carries the owner.sign-in step.
• --json id,name with a space no longer picks catalog and document fields; write --json=id,name.
• New global options from cli-core: -v, --trace, --no-input, --max-input-bytes, --brief, --full.
  Once a day an agent may see agents: drive skill install installs this tool's guide;
  drive <profile> config set --defaults skill_hint false turns it off.
• mcp serve --read-only makes every tool call read-only, as DRIVE_READ_ONLY=1 does. An agent's documents export,
  files download and files export still take only a file name, written in the profile's export folder.

Settings files and keyring entries written by drive 0.51 load unchanged (checked by contracts:upgrade).