feat: add Flyway migrations for PostgreSQL/TimescaleDB schema

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cameleer3-server-app/src/main/resources/db/migration/V5__route_diagrams.sql

@@ -0,0 +1,9 @@
+CREATE TABLE route_diagrams (
+    content_hash TEXT        PRIMARY KEY,
+    route_id     TEXT        NOT NULL,
+    agent_id     TEXT        NOT NULL,
+    definition   TEXT        NOT NULL,
+    created_at   TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE INDEX idx_diagrams_route_agent ON route_diagrams (route_id, agent_id);