Optimized the Kubernetes API calls. ~97% reduction, removed unused code

[EdwardCooke]

The counts are based on

• 19 ingresses
• 110 services
• 114 endpointslices
• 22 monitored services
• 21 monitored endpointslices
• 20 unique hostnames

Results

	Original	After your changes	Remaining
Per full sync	~860+	7	7
Per event (avg)	3–5	0–1	0–1
Steady state/min	~900+	~30	~30

[Copilot]

Pull request overview

This PR reduces Kubernetes API traffic by splitting the cache responsibilities: keeping cluster/hostname cache objects in Kubernetes while moving per-sync/per-event transient data (tracked services, endpoint counts, resource versions) into an in-memory cache, and removing the no-longer-used namespace manager.

Changes:

• Introduce an in-memory ICache implementation (MemoryCache + BasicCache) and a narrower IKubernetesCache abstraction backed by KubernetesApiCache.
• Remove INamespaceManager / DefaultNamespaceManager and adjust service registrations + constructors accordingly.
• Optimize KubernetesApiCache.SynchronizeCachesAsync by reusing already-listed hostname cache objects.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/Vecc.K8s.MultiCluster.Api/Vecc.K8s.MultiCluster.Api.csproj	Bumps dependencies and adds a caching-related package reference.
src/Vecc.K8s.MultiCluster.Api/Services/INamespaceManager.cs	Removes unused namespace manager interface.
src/Vecc.K8s.MultiCluster.Api/Services/IKubernetesCache.cs	Adds interface for Kubernetes-backed cache operations.
src/Vecc.K8s.MultiCluster.Api/Services/IBasicCache.cs	Adds abstraction over in-memory key/value cache.
src/Vecc.K8s.MultiCluster.Api/Services/Default/KubernetesApiCache.cs	Narrows responsibility to Kubernetes persistence + tweaks cache sync logic.
src/Vecc.K8s.MultiCluster.Api/Services/Default/DefaultServiceManager.cs	Removes namespace manager dependency from constructor.
src/Vecc.K8s.MultiCluster.Api/Services/Default/DefaultIngressManager.cs	Removes namespace manager dependency from constructor.
src/Vecc.K8s.MultiCluster.Api/Services/Default/DefaultHostnameSynchronizer.cs	Replaces AutoResetEvent gate with a boolean guard for local sync.
src/Vecc.K8s.MultiCluster.Api/Services/Default/DefaultCache.cs	New in-memory ICache implementation wrapping IBasicCache + IKubernetesCache.
src/Vecc.K8s.MultiCluster.Api/Services/Default/DefaultBasicCache.cs	New IBasicCache implementation backed by Microsoft.Extensions.Caching.Memory.
src/Vecc.K8s.MultiCluster.Api/Program.cs	Registers new caching services and removes namespace manager registration.
src/Vecc.K8s.MultiCluster.Api.Tests/Services/Default/DefaultServiceManagerTests.cs	Updates constructor usage after dependency removal.
src/Vecc.K8s.MultiCluster.Api.Tests/Services/Default/DefaultNamespaceManagerTests.cs	Removes tests for deleted namespace manager.
src/Vecc.K8s.MultiCluster.Api.Tests/Services/Default/DefaultIngressManagerTests.cs	Updates constructor usage after dependency removal.
src/Vecc.K8s.MultiCluster.Api.Tests/Services/Default/DefaultHostnameSynchronizerTests.cs	Updates constructor usage after dependency removal.

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