docs: add bill_history_ranges cleanup to FUTURE.md

FUTURE.md

@@ -688,3 +688,19 @@ Migration failures don't produce clear error messages or logs, making debugging
 - Include timing: `[migration] v0.20.0 completed in 234ms`
 - Log precondition checks: `[migration] Checking: table_exists('users')`
 - Error log with context: `[migration-error] v0.20.0 failed: UNIQUE constraint failed on users.username`
+
+---
+
+## Migration Cleanup: bill_history_ranges Outside Versioned Array
+**Priority:** LOW  
+**Status:** PENDING  
+**Added:** 2026-05-09 by Ripley
+
+**Description:**
+The `bill_history_ranges` table creation and a few other inline items are still outside the versioned migrations array in `db/database.js`. They run on every startup via `CREATE TABLE IF NOT EXISTS` but aren't tracked in `schema_migrations`, so they bypass the version tracking system.
+
+**Implementation Notes:**
+- Move `bill_history_ranges` and any other orphaned inline migrations into the versioned migrations array
+- Assign appropriate version numbers
+- Ensure idempotent `run()` functions for each
+- Verify they get tracked in `schema_migrations` after the move