refactor: Kill BaseObserver - migrate all observers to deps pattern

[yairfalse]

Summary

• Migrate all 6 observers from *base.BaseObserver embedding to lean *base.Deps pattern
• Delete BaseObserver struct and all its methods (~630 lines)
• Delete Observer interface entirely (~178 lines)
• Simplify telemetry to not require observer health checks

Changes by Observer

Observer	Pattern Change
deployments	NewDeploymentsObserver(name, config) → New(config, deps)
scheduler	NewSchedulerObserver(name, config) → New(config, deps)
container	Remove BaseObserver, add Run(ctx) with errgroup
node	Remove BaseObserver, add Run(ctx)
container-api	Remove BaseObserver, add Run(ctx)
container-runtime	Remove BaseObserver, add Run(ctx)

New Pattern

type Observer struct {
    name   string
    deps   *base.Deps
    logger zerolog.Logger
    config Config
}

func New(config Config, deps *base.Deps) (*Observer, error)
func (o *Observer) Run(ctx context.Context) error  // blocks until cancelled

Metrics/Emitter Access

• o.deps.Metrics.RecordEvent(o.name, eventType)
• o.deps.Metrics.RecordError(o.name, eventType, errorType)
• o.deps.Emitter.Emit(ctx, event)

Test plan

• All internal/base tests pass
• All observer tests pass
• Full project builds
• go vet and golangci-lint pass

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR refactors all 6 observers from an inheritance-based BaseObserver pattern to a lean dependency injection pattern using *base.Deps. The changes eliminate approximately 808 lines of code by removing the BaseObserver struct, Observer interface, and associated methods. The refactoring standardizes observer construction and execution while simplifying telemetry by removing observer health checks.

Key Changes:

• Migrated all observers to use New(config, deps) constructor pattern instead of NewXxxObserver(name, config)
• Replaced Start(ctx)/Stop() lifecycle with blocking Run(ctx) method
• Switched from BaseObserver embedding to direct *base.Deps field for accessing metrics and emitter
• Removed observer health check logic from telemetry endpoints (/ready now always returns 200 like /health)

Reviewed changes

Copilot reviewed 22 out of 22 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
internal/observers/scheduler/observer.go	Refactored to use deps pattern; Run() method blocks until context cancelled; metrics builder error handling changed
internal/observers/scheduler/observer_test.go	Updated all tests to use new constructor signature and Run() lifecycle
internal/observers/scheduler/events_watcher*.go	Updated tests to create observers using new pattern
internal/observers/node/observer.go	Removed BaseObserver embedding; added Run() method with blocking behavior
internal/observers/node/observer_test.go	Updated tests for new constructor and Run() pattern
internal/observers/deployments/observer.go	Migrated to deps pattern; simplified Run() to directly run informer
internal/observers/deployments/observer_*_test.go	Updated all test files to use new constructor and deps injection
internal/observers/container/observer.go	Added errgroup for concurrent stage management in Run()
internal/observers/container-runtime/observer.go	Consolidated Start/Run into single Run() method with inline cleanup
internal/observers/container-api/observer.go	Removed stopCh channel in favor of context-based cancellation
internal/observers/container-api/observer_test.go	Updated tests; removed health check and Start/Stop tests
internal/base/telemetry.go	Removed observer parameter and health checking from InitTelemetry; /ready endpoint simplified
internal/base/telemetry_test.go	Removed observer health check tests; simplified ready endpoint test
internal/base/observer.go	Deleted entire file (BaseObserver and Observer interface)
internal/base/observer_test.go	Deleted entire test file

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