chore(ops): centralize OpsRequest condition reason literals and fix message typos

[weicao]

Summary

No behavior change. Centralizes the inline Reason string literals in apis/operations/v1alpha1/opsrequest_conditions.go into named constants in the same file, and corrects three user-visible message typos in pkg/operations.

This is the first slice of the OpsRequest status reason model work; it intentionally adds nothing else (no new vocabulary, no catalog/registry, no phase changes, no evidence backfill). Subsequent slices will introduce the structured anchor reasons and the catalog on top of these constants.

What changed

Reason constants centralized

The NewXxxCondition constructors previously set Condition.Reason to inline string literals (e.g. "VolumeExpansionStarted"). The literal values are unchanged; they are now declared once in the existing constants block and referenced from each constructor. 16 new exported constants:

Constant	Value
ReasonValidateOpsRequestPassed	ValidateOpsRequestPassed
ReasonOpsRequestProcessedSuccessfully	OpsRequestProcessedSuccessfully
ReasonRestartStarted	RestartStarted
ReasonStartToRebuildInstances	StartToRebuildInstances
ReasonSwitchoverStarted	SwitchoverStarted
ReasonVerticalScalingStarted	VerticalScalingStarted
ReasonHorizontalScalingStarted	HorizontalScalingStarted
ReasonVolumeExpansionStarted	VolumeExpansionStarted
ReasonExposeStarted	ExposeStarted
ReasonVersionUpgradeStarted	VersionUpgradeStarted
ReasonStopStarted	StopStarted
ReasonStartCluster	StartCluster
ReasonReconfigureStarted	ReconfigureStarted
ReasonReconfigureFailed	ReconfigureFailed
ReasonBackupStarted	BackupStarted
ReasonRestoreStarted	RestoreStarted

Typo fixes (English grammar in user-visible failure messages)

File:Line	Before	After
pkg/operations/rebuild_instance.go:112	instance "%s" is availabled, can not rebuild it	instance "%s" is available, can not rebuild it
pkg/operations/rebuild_instance.go:491	the replicas of the component "%s" has been modifeied by another operation	the replicas of the component "%s" has been modified by another operation
pkg/operations/custom.go:305	cannot found the component "%s" in cluster "%s"	cannot find the component "%s" in cluster "%s"

These messages are surfaced via intctrlutil.NewFatalError and end up in OpsRequest.status and reconciler logs, so they are externally visible.

New tests

• TestReasonConstantsStringDrift pins the literal value of every Reason constant. A silent rename or string change fails the test, defending consumers that match on the Reason string value rather than the Go identifier.
• TestNewConditionReasonsMatchConstants verifies that each NewXxxCondition constructor returns a Condition whose Reason equals the centralized constant. Defends against an accidental in-place edit that re-introduces an inline string literal.

Test plan

• go test ./apis/operations/v1alpha1/... (4 tests, including the two new ones) — passes
• go test ./pkg/operations/util/... — passes (8.8s)
• go test ./pkg/operations/... (full Ginkgo suite, envtest 1.26.1) — passes (28.8s)
• go test ./controllers/operations/... — passes (17.9s)
• go vet ./apis/operations/v1alpha1/... ./pkg/operations/... — clean
• Repo-wide search for the three typo tokens (modifeied, availabled, cannot found) returns zero matches after this change.

Out of scope (subsequent slices)

• Adding new structured anchor reasons (e.g. for queue-blocked, precheck-failed, pod/job-failed, kbagent-action-failed, dependent-operation-failed, timeout-waiting-for-ready). These are introduced in a follow-up alongside a new reason catalog/registry file.
• Phase change for queue-full handling (currently Failed; tracked separately).
• Evidence backfill at terse-message paths (backup.go, restore.go, rebuild_instance_inplace.go, ops_manager.go).
• A make verify lint analyzer enforcing registered reasons and required evidence.

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[weicao]

QA review pass for Slice A.

Checked scope against OPS-S1 v1 boundary:

• Reason values are centralized without string drift; constructors now point at constants.
• Added drift guards cover both constant literal values and constructor Reason values.
• Typo fixes are user-visible message cleanup only; no phase/control-flow/evidence behavior change.
• custom.go:305 wording cannot find the component is acceptable and clearer than a mechanical not found replacement.

Local spot validation:

• go test ./apis/operations/v1alpha1/... passes.
• rg "modifeied|availabled|cannot found" . returns no matches.

Only remaining blocker I see is the GitHub branch-name gate (feat/... should become feature/...).