fix: add DevServer.get_runner_async hook for memory service support

[RuJ2]

Problem

veadk web uses DevServer (google-adk 2.x), but the memory-service hook only patches AdkWebServer.get_runner_async. Since DevServer is not a subclass of AdkWebServer, the hook never runs, long_term_memory is never injected into the Runner, and LoadMemoryTool always returns empty results.

Class hierarchy in google-adk 2.x

ApiServer              <- defines get_runner_async
  ^
DevServer              <- what veadk web actually creates (fast_api.py:558)
  ^
AdkWebServer           <- DEPRECATED, but this is the only class veadk hooks

Root Cause

google-adk 2.0.0 refactored the Server class hierarchy and deprecated AdkWebServer. veadk 1.0.0 still hooks only AdkWebServer, so the monkey-patch is ineffective when DevServer is used.

veadk dependency declaration (google-adk with no version constraint) allows google-adk 2.x to be installed, exposing this incompatibility.

Fix

Also hook DevServer.get_runner_async alongside the existing AdkWebServer hook. This ensures the memory service is injected regardless of which Server class is instantiated.

Testing

• Verified that veadk web now correctly injects LongTermMemory into the Runner
• LoadMemoryTool returns expected results from long-term memory

Notes

Longer-term fixes to consider:

1. Pin google-adk>=1,<2 in dependencies (breaking change for users on 2.x)
2. Fully adapt to google-adk 2.x API changes and drop the deprecated AdkWebServer hook