erdify 0.12.0 — UNIQUE foreign keys render as 1:1

[FabianClemenz]

erdify 0.12.0 is out 🎉

The erdify[sql] DDL frontend now understands that a single-column UNIQUE foreign key is a 1:1 relationship, and draws it accordingly instead of the previous blanket N:1.

• Correct 1:1 cardinality, written child … parent: |o--|| when the FK column is NOT NULL, |o--o| when it is nullable. The child end is |o because a UNIQUE FK caps a parent at at most one child — it never forces one to exist.
• Both UNIQUE forms are recognized: column-level col … UNIQUE and single-column table-level UNIQUE (col) — anonymous or named CONSTRAINT … UNIQUE (col). Composite UNIQUE (a, b) stays out of scope.
• A unique non-primary-key column is now flagged UK in the entity block, and --format json gains a unique boolean per field.
• Purely additive — the Python / SQLAlchemy / Pydantic frontends are unaffected, and the core install stays dependency-free.

pip install --upgrade "erdify[sql]"   # 0.12.0
erdify schema.sql -o erd.puml

Given this DDL:

CREATE TABLE customer (id INTEGER PRIMARY KEY);
CREATE TABLE customer_profile (
    id          INTEGER PRIMARY KEY,
    customer_id INTEGER NOT NULL UNIQUE REFERENCES customer(id)
);

erdify now emits a 1:1 edge:

customer_profile |o--|| customer : "customer_id"

(previously customer_profile }o--|| customer — a misleading N:1).

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