refactor: modularize email module and use actor for email verification (#1625)

backend/resources/migrations/postgres/20260727120000_email_verification_actors.down.sql

@@ -0,0 +1,10 @@
+CREATE TABLE email_verification_tokens
+(
+    id         UUID PRIMARY KEY,
+    created_at TIMESTAMPTZ NOT NULL,
+    token      TEXT        NOT NULL UNIQUE,
+    expires_at TIMESTAMPTZ NOT NULL,
+    user_id    UUID        NOT NULL REFERENCES users ON DELETE CASCADE
+);
+
+CREATE INDEX idx_email_verification_tokens_expires_at ON email_verification_tokens (expires_at);

backend/resources/migrations/postgres/20260727120000_email_verification_actors.up.sql

@@ -0,0 +1 @@
+DROP TABLE email_verification_tokens;