[APIView] WI-14: Approval Inheritance Policy & ClassifyTransition

## Goal

Define the per-language approval inheritance policy and the version-transition classifier.

**Area:** Approvals · **Depends on:** Nothing (parallel with WI-1) · **Stable alone:** ✅ Yes — pure infrastructure, no behavior change

## Deliverables

### Configuration

Add keys to Azure App Configuration:
- `ApprovalInheritancePolicy:Default` — JSON blob per `ApprovalInheritancePolicyOptions` schema (§4.6.1)
- `ApprovalInheritancePolicy:{Language}` — Language-specific overrides (optional)

Create `APIViewWeb/Models/ApprovalInheritancePolicyOptions.cs` with `InheritanceRule` enum and six transition fields. Register as `IOptionsSnapshot>`.

### Implement `ClassifyTransition()`

Static method in `VersionNormalizationHelper.cs`:
1. Parse both versions' `VersionIdentifier` via `AzureEngSemanticVersion`
2. Determine transition kind: `PrereleaseToPrerelease`, `PrereleaseToStable`, `StableToPrerelease`, `StablePatch`, `StableMinor`, `StableMajor`
3. Look up rule in per-language policy (fallback to `Default`)

### Tests

- `VersionNormalizationTests.cs` — `ClassifyTransition` for all 6 transition kinds; language-specific overrides; default fallback

Start with the ApprovalInheritancePolicyOptions schema in the issue and the existing Azure App Configuration registration patterns. Implement the policy and ClassifyTransition work in APIViewWeb/Models/ApprovalInheritancePolicyOptions.cs and VersionNormalizationHelper.cs, then run VersionNormalizationTests.cs; done means all six transition kinds, language overrides, and default fallback are covered.

Written by the indexing model from the issue text.