fix(i18n): localize PR merge/close confirmations and merge method labels (#28568)

PR close/reopen/merge confirmation titles were built from a fragment
template ("{{value0}} PR #{{value1}}?"), so locales could not reorder the
verb, and merge method labels came from English-only shared constants.

Add whole-sentence title keys per action and merge method plus translated
merge method labels in a renderer copy module, and route every PR surface
(item dialog, PR page, Tasks MergeCell, right-sidebar HostedReviewActions)
through it. Drop the English labels from the shared merge-method
presentation and remove the dead fragment keys from all locales.

Co-authored-by: Neil <4138956+nwparker@users.noreply.github.com>

src/shared/github/pull-request-merge-methods.test.ts

@@ -8,12 +8,7 @@ describe('GitHub PR merge methods', () => {
   it('keeps the historical squash-first fallback when repository metadata is missing', () => {
     expect(resolveGitHubPRMergeMethods()).toEqual({
       defaultMethod: 'squash',
-      defaultLabel: 'Squash and merge',
-      methods: [
-        { method: 'squash', label: 'Squash and merge' },
-        { method: 'merge', label: 'Create merge commit' },
-        { method: 'rebase', label: 'Rebase and merge' }
-      ]
+      methods: ['squash', 'merge', 'rebase']
     })
   })
 
@@ -27,11 +22,7 @@ describe('GitHub PR merge methods', () => {
 
     expect(resolveGitHubPRMergeMethods(settings)).toEqual({
       defaultMethod: 'rebase',
-      defaultLabel: 'Rebase and merge',
-      methods: [
-        { method: 'rebase', label: 'Rebase and merge' },
-        { method: 'squash', label: 'Squash and merge' }
-      ]
+      methods: ['rebase', 'squash']
     })
   })
 
@@ -44,8 +35,6 @@ describe('GitHub PR merge methods', () => {
     })
 
     expect(settings?.defaultMethod).toBe('merge')
-    expect(resolveGitHubPRMergeMethods(settings).methods).toEqual([
-      { method: 'merge', label: 'Create merge commit' }
-    ])
+    expect(resolveGitHubPRMergeMethods(settings).methods).toEqual(['merge'])
   })
 })

src/shared/github/pull-request-merge-methods.ts

@@ -2,21 +2,9 @@ import type { GitHubPRMergeMethod, GitHubPRMergeMethodSettings } from './pull-re
 
 export const GITHUB_PR_MERGE_METHODS = ['squash', 'merge', 'rebase'] as const
 
-export const GITHUB_PR_MERGE_METHOD_LABELS: Record<GitHubPRMergeMethod, string> = {
-  squash: 'Squash and merge',
-  merge: 'Create merge commit',
-  rebase: 'Rebase and merge'
-}
-
-export type GitHubPRMergeMethodOption = {
-  method: GitHubPRMergeMethod
-  label: string
-}
-
 export type GitHubPRMergeMethodPresentation = {
   defaultMethod: GitHubPRMergeMethod
-  defaultLabel: string
-  methods: GitHubPRMergeMethodOption[]
+  methods: GitHubPRMergeMethod[]
 }
 
 function allMethodsAllowed(): Record<GitHubPRMergeMethod, boolean> {
@@ -79,15 +67,8 @@ export function resolveGitHubPRMergeMethods(
     defaultMethod,
     ...GITHUB_PR_MERGE_METHODS.filter((method) => method !== defaultMethod)
   ].filter((method) => allowedMethods[method])
-  const methods = (orderedMethods.length > 0 ? orderedMethods : GITHUB_PR_MERGE_METHODS).map(
-    (method) => ({
-      method,
-      label: GITHUB_PR_MERGE_METHOD_LABELS[method]
-    })
-  )
   return {
     defaultMethod,
-    defaultLabel: GITHUB_PR_MERGE_METHOD_LABELS[defaultMethod],
-    methods
+    methods: orderedMethods.length > 0 ? orderedMethods : [...GITHUB_PR_MERGE_METHODS]
   }
 }