Rewrite all acp_adapter imports to hermes_agent.acp in source, tests,
and pyproject.toml. Convert relative imports to absolute per manifest
convention. Strip sys.path hack from entry.py (redundant with editable
install). Update pyproject.toml entry point and packages.find.
Part of #14586, #14182
Clients like acp-bridge send periodic bare `ping` JSON-RPC requests as a
liveness probe. The acp router correctly returns JSON-RPC -32601 to the
caller, which those clients already handle as 'agent alive'. But the
supervisor task that ran the request then surfaces the raised RequestError
via `logging.exception('Background task failed', ...)`, dumping a full
traceback to stderr on every probe interval.
Install a logging filter on the stderr handler that suppresses
'Background task failed' records only when the exception is an acp
RequestError(-32601) for one of {ping, health, healthcheck}. Real
method_not_found for any other method, other exception classes, other log
messages, and -32601 logged under a different message all pass through
untouched.
The protocol response is unchanged — the client still receives a standard
-32601 'Method not found' error back. Only the server-side stderr noise is
silenced.
Closes#12529
