Creator tax compliance (#4254)

* Initial implementation

* Remove test code

* Query cache

* Appease clippy

* Precise TIN/SSN

* Make tax threshold customizable via env variable

* Address review comments

apps/labrinth/migrations/20250823233518_user-compliance.sql

@@ -0,0 +1,17 @@
+CREATE TABLE users_compliance (
+    id                     BIGSERIAL PRIMARY KEY,
+    user_id                BIGINT NOT NULL REFERENCES users(id),
+
+    requested              TIMESTAMP WITH TIME ZONE NOT NULL,
+    signed                 TIMESTAMP WITH TIME ZONE,
+    e_delivery_consented   BOOLEAN NOT NULL,
+    tin_matched            BOOLEAN NOT NULL,
+    last_checked           TIMESTAMP WITH TIME ZONE NOT NULL,
+
+    external_request_id    VARCHAR NOT NULL,
+    reference_id           VARCHAR NOT NULL,
+
+    form_type              VARCHAR NOT NULL,
+
+    UNIQUE (user_id)
+);