GH-1611: Add health indicators for Qdrant and Weaviate

[DDINGJOO]

Summary

This PR adds Actuator health indicators for two external vector stores:

• Qdrant
• Weaviate

The indicators are conditionally auto-configured and can be disabled with:

• management.health.qdrant.enabled=false
• management.health.weaviate.enabled=false

Why

Issue #1611 requests health indicators for vector stores that can become unavailable independently from the application.

Changes

• Added QdrantVectorStoreHealthAutoConfiguration
• Added WeaviateVectorStoreHealthAutoConfiguration
• Registered both in each module's AutoConfiguration.imports
• Added optional dependency org.springframework.boot:spring-boot-health in both autoconfigure modules
• Added unit tests for both health auto-configurations

Behavior

Qdrant health indicator:

• Calls QdrantClient.healthCheckAsync(Duration.ofSeconds(5))
• Reports UP with details (title, version, optional commit, host, port)
• Reports DOWN on exception

Weaviate health indicator:

• Calls weaviateClient.misc().liveChecker().run()
• Reports UP when result is true and no errors
• Reports DOWN when response has errors, result is false/null, or exception occurs
• Includes details (live, hasErrors, optional error, host)

Tests

Qdrant:

• should be UP on healthy response
• should be DOWN on client failure
• should not register when management.health.qdrant.enabled=false
• should back off when custom qdrantHealthIndicator bean is provided

Weaviate:

• should be UP on healthy response
• should be DOWN when response has errors
• should be DOWN when run() throws
• should not register when management.health.weaviate.enabled=false
• should back off when custom weaviateHealthIndicator bean is provided

Build Verification

• ./mvnw -pl auto-configurations/vector-stores/spring-ai-autoconfigure-vector-store-qdrant -Dmaven.build.cache.enabled=false -Denforcer.skip=true -Dkotlin.compiler.skip=true test
• ./mvnw -pl auto-configurations/vector-stores/spring-ai-autoconfigure-vector-store-weaviate -Dmaven.build.cache.enabled=false -Denforcer.skip=true -Dkotlin.compiler.skip=true test

Related to #1611