FIX revert alembic version

[hannahwestra25]

Problem

alembic migration chain broken for any existing database because the migration 108a72344872 (add_labels_to_attack_results) was deleted and it's columns squashed— plus new error/retry columns — directly into the initial schema (e373726d391b)

Any database that had already run migrations is stamped at revision 108a72344872 in the alembic_version table. Since that revision file no longer exists, alembic throws:
Can't locate revision identified by '108a72344872'

This breaks all integration tests and any existing user or CI database.

Why this approach

Restore the deleted migration + create a new one (this PR)

• It preserves the published revision chain. Migrations that have been applied to any database must never be deleted or modified — this is a fundamental rule of schema migration systems. Restoring 108a72344872 makes existing databases immediately functional again.
• It works for both existing and new databases. Existing DBs (stamped at 108a72344872) simply run the new migration to get error columns. Fresh DBs run all three migrations in order. Option 2 would require existing DBs to first recognize a revision they've never seen, adding fragile re-stamping logic.
• It avoids duplication. Squashing columns into the initial schema while also having them in a later migration would cause "column already exists" errors on fresh databases. Reverting the initial schema to its original form keeps each column defined in exactly one place.

Changes

File	Change
e373726d391b_initial_schema.py	Reverted to original — removed 9 columns that were incorrectly squashed in
108a72344872_add_labels_to_attack_results.py	Restored deleted migration (adds labels to AttackResultEntries)
7a1b2c3d4e5f_add_error_retry_fields.py	New migration — adds error/retry columns to AttackResultEntries and ScenarioResultEntries

Final migration chain: e373726d391b → 108a72344872 → 7a1b2c3d4e5f

Testing

• test_migration.py — 16/16 passed
• test_sqlite_memory.py + test_azure_sql_memory.py — 73 passed, 1 skipped
• enforce_alembic_revision_immutability.py — passed