agent/reset returns true even when the agent has no reset hook

[aniketwattamwar]

Problem

In sdk/python/src/ecp/server.py, _handle_reset runs the hook if one is registered and returns true either way:

def _handle_reset():
    method_name = _HOOKS["reset"]
    if method_name:
        handler = getattr(_CURRENT_AGENT_INSTANCE, method_name)
        _invoke_handler(handler)
    return True

An agent with no @on_reset claims a successful reset. Scenario isolation silently does not happen, and state leaks between scenarios while the runtime believes it was cleared.

Proposal
Tie this to the reset capability (#TBD). Agents without the hook stop declaring reset, and the runtime warns on multi-scenario runs instead of being lied to.

Acceptance criteria

• reset capability reflects whether a hook is actually registered
• Runtime warns when running multiple scenarios against an agent without it
• Test covering an agent with no @on_reset