feat(14-01): generate and apply Drizzle migration 0010 for multi-signer columns

- Migration 0010_sharp_archangel.sql adds signer_email to signing_tokens
- Migration adds signers JSONB column to documents
- Migration adds completion_triggered_at TIMESTAMP to documents
- Additive-only: no DROP columns, no ALTER TYPE, no backfills
- Applied successfully to local Neon/Postgres instance

teressa-copeland-homes/drizzle/0010_sharp_archangel.sql

@@ -0,0 +1,3 @@
+ALTER TABLE "documents" ADD COLUMN "signers" jsonb;--> statement-breakpoint
+ALTER TABLE "documents" ADD COLUMN "completion_triggered_at" timestamp;--> statement-breakpoint
+ALTER TABLE "signing_tokens" ADD COLUMN "signer_email" text;