Revise HIVE-0002 to v2.0 with a worked example and attribute-unit golden record selection

[RobGrafrath]

What this changes and why

HIVE-0002 described entity matching and the golden record abstractly, and community feedback showed the mechanics deserve concrete grounding. This adds a Worked Example section that walks one consumer's records through programmatic matching, a manual merge and its later unmerge, golden record composition, and source retention. The example makes three behaviors explicit: the golden record composes attribute by attribute and selects each multi-field attribute (a name, an address) as a whole unit rather than assembling components from different source records; completeness matters, so a fuller, older name is retained over a newer bare initial; and recency of client-supplied values is judged by the client's aging dates, with contact outcome history corroborating an address switch.

The Decision section and The Golden Record section previously said "best available value for each field," which invited a column-level misreading that could produce an address no source ever reported. Both now say "attribute" and state the whole-unit selection rule. The INDEX.md line for HIVE-0002 is updated to match the revised Decision sentence.

Interacting decisions

• HIVE-0002 Entity Matching, Golden Record, and Locale-Aware Identity Resolution: the decision revised here.
• HiveAR Design Decision 3: the worked example cross-references its contact outcome history dimension, consistent with the full scoring engine already named in HIVE-0002's v3+ phasing.
• HiveAR Design Decision 1: the example relies on its entity and account separation; no change to it.

No decision is contradicted.

Version bumps

HIVE-0002: major, 1.0 to 2.0, because the Decision section sentence changed in substance (field-level to attribute-unit golden record selection). The date moves to 2026-09-01. No other decision file changes.

Checklist

• I read the decisions neighboring this change, not just the file I edited.
• New or retitled decisions have a matching line in INDEX.md, and front matter follows CONTRIBUTING.md.
• python3 scripts/validate.py --base main passes locally, or I am relying on CI to tell me.
• No pricing, rates, market or customer allocation, consumer data, or client-confidential information.
• Claims about law or regulation are flagged for verification, not asserted.
• Commits are signed off (DCO). If I forgot, I will post the retroactive sign-off comment per CONTRIBUTING.md.
• I license this contribution under CC BY 4.0 (prose) and Apache 2.0 (embedded code samples).