[chore] reduce coupling to global vars

[ldmonster]

Overview

What this PR does / why we need it

This PR implements shell-operator refactoring. None of the changes alter runtime behaviour; they are all internal decoupling improvements that reduce coupling to global app.* state, remove shared mutable globals that block test isolation, and tighten a previously-silent failure path.

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1.1 — Replace app.* reads in business logic with injected configuration

Files: pkg/hook/hook_manager.go, pkg/shell-operator/kube_client.go, pkg/shell-operator/bootstrap.go, test/hook/context/generator.go

hook_manager.go — Three app.* reads (app.DebugKeepTmpFiles, app.LogProxyHookJSON, app.ProxyJsonLogKey) are replaced with fields stored on Manager (keepTemporaryHookFiles, logProxyHookJSON, logProxyHookJSONKey). The values are supplied through three new ManagerConfig fields. Bootstrap sets them from app.* at the composition root; the pkg/app import is removed from hook_manager.go.

kube_client.go — Introduces KubeClientConfig struct with explicit fields (Context, Config, QPS, Burst, Timeout). defaultMainKubeClient and defaultObjectPatcherKubeClient now accept a KubeClientConfig instead of reaching into app.* directly. The init* wrapper functions remain the only point that reads app.*, preserving clean separation between the composition root and infrastructure code. WithTimeout is now guarded with cfg.Timeout > 0 to avoid setting an unnecessary zero timeout on the main client.

test/hook/context/generator.go — Removes the pkg/app import; passes explicit zero/false values to hook.NewHook.

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1.2 — Remove DefaultFactoryStore global; inject via constructor

Files: pkg/kube_events_manager/factory.go, pkg/kube_events_manager/resource_informer.go, pkg/kube_events_manager/monitor.go, pkg/kube_events_manager/kube_events_manager.go, pkg/kube_events_manager/monitor_test.go, test/hook/context/generator.go

The DefaultFactoryStore package-level variable and its init() initialiser are removed. Instead:

• NewKubeEventsManager creates its own *FactoryStore per instance.
• monitor receives the store via its constructor (NewMonitor) and threads it through CreateInformersForNamespace → resourceInformerConfig.
• resourceInformer stores and uses ei.factoryStore in start() and wait() instead of the global.

Each test that creates a KubeEventsManager or a Monitor now gets an isolated FactoryStore, eliminating the shared-state race that could cause non-deterministic failures in parallel test runs. The manual DefaultFactoryStore.Reset() call in test/hook/context/generator.go is also removed as it is no longer needed.

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1.3 — Merge DebugKeepTmpFilesVar (string) into DebugKeepTmpFiles (bool)

Files: pkg/app/debug.go, pkg/hook/hook.go

Two variables represented the same concept: DebugKeepTmpFilesVar string (CLI flag sink, compared via != "yes") and DebugKeepTmpFiles bool (used at hook construction time). The string variable is removed; the CLI flag is re-wired directly to BoolVar(&DebugKeepTmpFiles). The app.DebugKeepTmpFilesVar != "yes" guard in hook.Run() is replaced with the h.KeepTemporaryHookFiles bool field that was already set at construction time, allowing the pkg/app import to be dropped from pkg/hook/hook.go.

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1.4 — Fix HookMetadataAccessor to return (HookMetadata, bool)

Files: pkg/hook/task_metadata/task_metadata.go, pkg/shell-operator/operator.go, pkg/shell-operator/operator_test.go, pkg/hook/task_metadata/task_metadata_test.go, pkg/task/queue/task_queue_compaction_test.go

HookMetadataAccessor previously returned a zero HookMetadata{} on both the nil-metadata and wrong-type-assertion paths, while only logging an error. Callers would continue with empty hook names and silently dispatch no-op work.

The function signature changes to (HookMetadata, bool). All three call sites in operator.go (taskHandler, taskHandleEnableKubernetesBindings, taskHandleHookRun) now explicitly short-circuit with Status: "Fail" when ok == false, preventing silent data corruption.

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1.5 — Rename ManagerConfig abbreviated fields (Kmgr, Smgr, Wmgr, Cmgr)

Files: pkg/hook/hook_manager.go, pkg/shell-operator/bootstrap.go, pkg/hook/hook_manager_test.go

The four fields in ManagerConfig used non-self-documenting abbreviations. They are renamed to match the types they carry:

Before	After
Kmgr	KubeEventsManager
Smgr	ScheduleManager
Wmgr	AdmissionWebhookManager
Cmgr	ConversionWebhookManager

All construction sites updated accordingly.