Decision record log

If AGENTS.md sets a different convention for this topic, follow AGENTS.md.

Where

docs/decisions/
├── README.md                          simplified list per type
├── 0001-users-table-schema.md
├── 0002-money-stored-in-cents.md
└── 0003-payment-client-behind-an-interface.md

• One file per decision: NNNN-short-title.md, with a four-digit number that never repeats.
• All decisions live in the same folder. The type is a field, not a folder.
• If the repository already keeps decision records in another folder or format, use that one.
• When a merge brings clashing numbers, the older branch keeps its numbers. Renumber the other after the highest one and update every reference (ADR NNNN, Superseded by NNNN, links).