H617A RC2 — response-driven segment verification

Includes the H617A controls and state-preservation work from RC1, rebased on v7.6.2 with #249 GATT fixes.

RC1 live testing found an outstanding background poll could supply old segment values to a later write's confirmation. RC2 holds the existing arbiter through complete segment replies, uses one deadline for query transmission and collection, and bounds cancellation cleanup. Abandoned batches require a fresh connection before control writes. No settling sleeps or healthy-path reconnects were added.

Software gate: 2,798 Python tests passed (79 skipped), 269 frontend unit tests, 33 browser tests and 132 protocol replays. Typing, lint, formatting and generated-output checks passed. Independent correctness/Ponytail review findings are resolved.

RC1 passed whole-strip power/brightness/RGB/Kelvin checks; its segment matrix stopped at the timing failure and restored the authorised off/5% warm baseline. RC2 must repeat those checks and complete the remaining matrix. Music/DIY rendering and onboard-microphone response await owner observation. ACK and selector readback do not establish resident-payload equality or rendering; indistinguishable same-subtype ACKs and duplicate query replies remain wire limitations.

New protocol coverage remains explicitly speculative. Unknown physical IC count still gates dependent controls. Qualification is limited to cupboard-skirt H617A HW 3.01.01 / FW 3.02.24. No stable release until qualification passes.

Install this exact tag through HACS. Runtime manifest: 7.7.0rc2. Every Home Assistant restart requires fresh owner approval.