AdCP 3.3: seller-side rules in decisioning (version literals, sales-fixed-rate, measurement terms, domain identifiers, domain list bounds) #1668

Spec (tag v3.3.0-beta.0, migration guide §Required to claim 3.3 behavior)

Seller-side rules the decisioning framework owns or should help with:

• Version literals: audit every "3.2" / startswith("3.2") check (accounts.py, decisioning/dispatch.py, signing/*, server/principal.py accepted_async_adcp_versions) for 3.3 inclusion (inventory §1, "Handler gate").
• sales-fixed-rate specialism: adcp.decisioning.specialisms support and the sales_fixed_rate storyboard. Provisional buys (confirmed_at: null) stay pending_start, overlapping AdCP 3.3: media-buy and webhook rules (provisional buys, revisions from any origin, optional webhook authentication, totals) #1644.
• Advertise only accepted measurement terms: TERMS_REJECTED must not fire for replayed advertised terms, and an advertised measurement_window references a declared window_id. Add a framework check on advertised products.
• Property domain identifiers: lowercase ASCII hostnames; invalid values are INVALID_REQUEST. Add a sender-side normalizer ("explicit conversion before submission") for property-list helpers.
• Counterparty-asserted domain lists: 100 entries, 253 characters each, a byte budget of 8 KiB per field and 16 KiB combined, plus the *_complete flags. A truncation helper for capability builders. Buyers never deny on absence.
• build_creative refinement: carries compliance forward (COMPLIANCE_UNSATISFIED) where the SDK owns creative refinement.
• CREATIVE_MERGE_REJECTED / RIGHTS_CHANNEL_VIOLATION: error-detail narrowing and minting helpers.
• evaluator_id: remove any SDK helper that still mints it.

Work (after #1662)

Triage each item against the code; implement the framework parts with tests, and split out any item that grows.

Inventory: docs/adcp-3.3-sdk-inventory.md §1, §5, §8. Batch C/D.