refactor: derive processor-route mapping from diagrams instead of executions

Store application_name in route_diagrams at ingestion time (V7 migration),
resolve from agent registry same as ExecutionController. Move
findProcessorRouteMapping from ExecutionStore to DiagramStore using a
JSONB query that extracts node IDs directly from stored RouteGraph
definitions. This makes the mapping available as soon as diagrams are
sent, before any executions are recorded.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/resources/db/migration/V7__diagram_application_name.sql

@@ -0,0 +1,2 @@
+ALTER TABLE route_diagrams ADD COLUMN IF NOT EXISTS application_name TEXT NOT NULL DEFAULT '';
+CREATE INDEX IF NOT EXISTS idx_diagrams_application ON route_diagrams (application_name);