* fix(memory): report non-mapping Honcho backend_config values as ValueError
failure_policy, workspace_overrides and user_peer_overrides were read with a
falsy-only `or {}` fallback, so a truthy non-mapping (a bare string, a YAML
list) reached .get/.items and escaped as a bare AttributeError from inside
backend construction. Route all three through one _mapping helper that keeps
falsy values meaning "unset" and names the offending key as a ValueError, the
posture the mem0 and OpenViking backends already take.
* fix(memory): name the Honcho numeric knobs that cannot be cast
timeout_seconds / connect_timeout_seconds / message_char_limit /
max_injection_chars still reached float() / int() with a YAML null or a
mapping, so the operator got a TypeError naming neither the key nor the
config file. Narrow all four through one _number helper that keeps falsy
values meaning "unset" the way the sibling api_key / storage_path scalars
already do, and reports a value that cannot be cast as a ValueError on the
key. Numeric strings keep parsing, since that is what float/int accept.
* fix(memory): report non-numeric backend_config knobs by name in mem0 and OpenViking
mem0 casts top_k, score_threshold, max_injection_chars and timeout_seconds, and
OpenViking casts timeout_seconds, max_seen_message_ids, retrieval.top_k and
retrieval.max_injection_chars, straight through int()/float(). A knob written
without a value in YAML therefore escapes as "TypeError: int() argument must be
a string..." from inside backend construction, naming neither which knob nor
which file is wrong, and a non-numeric value escapes as the equally anonymous
"could not convert string to float".
Both now resolve numeric knobs through a helper that keeps a value-less key at
its default, the way the same dicts already treat failure_policy and
allow_insecure_http, and turns an uncastable value into a ValueError that names
the knob. OpenViking's score_threshold keeps None as a meaningful value rather
than a default to fall back to.
