Make Prompt Runner an explicit ASM core-lane client instead of
defaulting through ASM auto lane and SDK-sensitive preflight checks.

Drop provider SDK deps from the package, replace runtime preflight
with ASM provider/core metadata, and update scaffolding, examples,
docs, and tests to use provider-facing config.

Keep local example runners self-contained by installing
agent_session_manager alongside the local Prompt Runner path dep,
while still avoiding direct provider SDK packages.