The optional variant of get_agent_auth_context had accept_authorization=False,
which prevented agents using Authorization: Bearer from passing through the
ACTOR_DEP / BOARD_READ_DEP / TASK_DEP dependency chain.
This caused 401 on any agent route that resolves a board or task via the shared
ACTOR_DEP (e.g. PATCH /agent/boards/{id}/tasks/{id} and
POST /agent/boards/{id}/tasks/{id}/comments), even though the same token worked
fine on routes that use AGENT_CTX_DEP directly (accept_authorization=True).
Fix: set accept_authorization=True in get_agent_auth_context_optional so both
X-Agent-Token and Authorization: Bearer are accepted consistently.
Verified: PATCH and POST /comments now resolve board/task correctly when
Authorization: Bearer is used. No security regression — agent_token_hash
comparison rejects any non-agent bearer tokens.
