Merged PR 2374: addeding domain layer extrraction

# Summary

This PR introduces a **Case Lifecycle Domain Boundary** to centralize lifecycle decision logic and reduce coupling within the appeals application.

The work is **behaviour-preserving** and introduces no intentional changes to business rules, CRM integrations, translations, dashboards, API routes, or user-facing functionality.

## What was added

New lifecycle boundary:

```text
lib/domain/case-lifecycle/
```

Key responsibilities extracted:

- Specialist process normalization
- Appeal type mapping
- Specialist process stage override mapping
- Stage case-type resolution
- Stage catalogue lookup
- Closed-case status recognition
- Lifecycle stage index resolution
- Lifecycle stage status assignment

## Behaviour preserved

Characterization tests were added before each extraction to preserve:

- Appeal type mapping and aliases
- Specialist process handling
- Lifecycle stage progression
- Closed-case handling
- Status assignment (`complete`, `in-progress`, `not-started`)
- Existing ROW behaviour
- Existing `statuscode` lifecycle semantics

Closed-case recognition remains unchanged for:

```text
1000
5
6
846040013
846040059
846040060
```

## Documentation

Added:

```text
lib/domain/case-lifecycle/README.md
```

Documenting:

- Boundary ownership
- Non-goals
- Lifecycle invariants
- Known architectural constraints
- Future extraction roadmap

## Testing

Added lifecycle characterization coverage for:

- Stage wrapper behaviour
- Specialist process normalization
- Appeal type mapping
- Specialist process stage mapping
- Stage case-type resolution
- Stage catalogue lookup
- Progress behaviour
- Closed-case status handling
- Stage index resolution
- Stage status assignment

## Validation

- Lifecycle characterization tests passed
- `npm run lint` passed with no errors

## Out of Scope

No changes to:

- Stage catalogue ownership
- Representation eligibility
- Dashboard calculations
- CRM/OData queries
- API routes
- Redux state
- EN/CY translations
- Event visibility logic

## Risk

**Low risk**

The refactor was delivered through small, characterization-first slices with no functional changes intended.

Related work items: #23527

lib/representation/pageLoaders.js

@@ -10,6 +10,7 @@ import {
 import { getRepsFromBlob } from "../../actions/services/documentService";
 import { getBasicSearch } from "../../actions/services/searchService";
 import { consoleLogger } from "../../actions/core/logger";
+import { normalizeSpecialistProcess } from "../domain/case-lifecycle";
 import {
     getFormCollectionByID,
     getSearchDetails
@@ -280,16 +281,9 @@ export const loadNewRepresentation = async ({ store, ctx, bootstrap }) => {
             "currentType": "myRepresentations",
             "incidentid": searchResultsObj?.value?.[0]?.incidentid,
             "appealType": searchResultsObj?.value?.[0]?.pinswg_appealcasetype,
-            "specialistProcess":
+            "specialistProcess": normalizeSpecialistProcess(
                 searchDetailsObj?.[0]?.value?.[0]
-                    ?.pinswg_speacialistcaseprocess != null ||
-                searchDetailsObj?.[0]?.value?.[0]
-                    ?.pinswg_specialistcaseprocess != null
-                    ? searchDetailsObj?.[0]?.value?.[0]
-                          .pinswg_speacialistcaseprocess ||
-                      searchDetailsObj?.[0]?.value?.[0]
-                          .pinswg_specialistcaseprocess
-                    : ""
+            )
         })
     );