fix: add kind: standalone to override Hermes v0.11.0 memory provider auto-detection

Hermes v0.11.0 auto-detects plugins containing MemoryProvider in
__init__.py and coerces them to kind: exclusive, which prevents the
general PluginManager from loading them. Since this plugin uses the
dual-path approach (memory provider + standalone tools/hooks), the
auto-detection was blocking tool registration.

Explicit kind: standalone tells Hermes to load this as a regular
plugin, allowing tools (mem0_profile, mem0_search, mem0_conclude,
mem0_delete) and the pre_llm_call hook to register correctly.

plugin.yaml

@@ -3,6 +3,7 @@ version: "1.0.0"
 description: "Mem0 local server memory provider (self-hosted)"
 author: "Henry Hofmann"
 manifest_version: 1
+kind: standalone
 
 requires_env:
   - name: MEM0_BASE_URL