fix(precompute): enforce frame replay lineage

[zzylol]

Closes #589.

Implements receiver-side frame validation and replay state for ObserveEnvelope:

• canonical ASAP-FRAME-V1 SHA-256 sealing and verification;
• duplicate delivery is an idempotent no-op;
• sequence gaps, conflicting replays, and unknown delta bases return typed errors before sketch mutation;
• sender attaches the checksum after the payload is finalized;
• framed envelope processing is serialized per precompute instance so validation/application/commit is atomic.

Legacy envelopes without frame attributes remain accepted for compatibility.

Tests cover exact replay, gap, bad base, and payload corruption.

Validation: go test . ./controlchannel ./monitor ./sketches

[zzylol]

Follow-up review fix: receiver replay state is now bounded by MaxSeries (100k safety default when unset) with LRU retirement. A frame for a retired lineage must restart at sequence 1/full checkpoint or returns the existing typed gap/base error for resync.