prefect server in zig

add state_transition_id to flow_runs schema

also fix empirical_policy type: JSONB -> TEXT for consistency with sqlite

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

+2 -1
+2 -1
src/db/schema/postgres.zig
··· 44 44 \\ work_queue_id TEXT, 45 45 \\ auto_scheduled INTEGER DEFAULT 0, 46 46 \\ idempotency_key TEXT, 47 - \\ empirical_policy JSONB DEFAULT '{}' 47 + \\ empirical_policy TEXT DEFAULT '{}', 48 + \\ state_transition_id TEXT 48 49 \\) 49 50 , .{}); 50 51