v2.33.4 — readback verification framework

Internal reliability framework.

• Added verify_by_readback (src/utils/readback.py) — a primitive for mutating Resolve ops that verifies an action by reading the real post-state back instead of trusting the API's frequently-unreliable return value. A contradiction (reported success but a failing readback) is logged as a reliability signal.
• Changed Auto-sync audio runs through verify_by_readback as its first user and reports a verified field alongside linked/newly_linked. Behavior unchanged; the bespoke readback loop is replaced by the shared primitive.

Foundation for routing more unreliable ops (AppendToTimeline id-recovery, setters) through readback verification. Live-validated on DaVinci Resolve Studio 21.0.0.