Make magic link single use and reduce duration to 15min

Signed-off-by: Émile Ré <emile@getprobo.com>

pkg/coredata/migrations/20260116T104702Z.sql

@@ -0,0 +1,6 @@
+CREATE TABLE iam_tokens (
+    id TEXT PRIMARY KEY,
+    hashed_value BYTEA NOT NULL,
+    created_at TIMESTAMP WITH TIME ZONE NOT NULL,
+    CONSTRAINT iam_tokens_hashed_value_unique UNIQUE (hashed_value)
+);