Each AgentProvider now owns its skills / prompt / provision /
supervise_mcp end-to-end. The base ABC declares all four as
abstract; ClaudeAgentProvider and CodexAgentProvider each carry
their own copy loop.
Per PR review feedback (review #128): the shared
_provision_apply.py abstraction was weak — Claude and Codex
harnesses already diverge (codex's dummy-auth + login-status
verify has no claude analogue) and forcing both onto one helper
just postpones the split. Duplication is intentional.
Deletes bot_bottle/_provision_apply.py and consolidates testing
under tests/unit/test_contrib_{claude,codex}_provider.py (one
file per provider, covering all four methods).
