Each non-LGP integration carried its own drifted/stale copy of the e2e specs, causing
inconsistent behavior and noisy diffs across the fleet. Copied langgraph-python's canonical
specs verbatim across ~15 integrations (576 spec files total, SHA-1-verified identical to
LGP) so every integration runs the same assertions.
Also removed 2 orphan specs whose underlying demo pages do not exist:
- showcase/integrations/agno/tests/e2e/hitl-in-chat-booking.spec.ts
- showcase/integrations/built-in-agent/tests/e2e/shared-state-write.spec.ts
Integration-specific variant specs were intentionally left as-is: reasoning-default-render,
byoc-*, agentic-chat-reasoning, and shared-state-write where the demo exists. google-adk and
langgraph-typescript were already in parity from earlier commits and show no new changes.
The showcase framework directories better reflect their role as
integration examples rather than distributable packages.
Renames showcase/packages/ -> showcase/integrations/ and updates
the test docker-compose file reference accordingly.