fix: cherry-pick PR #15695 — replace 33 missing NLS keys causing blank wizard options

[Copilot]

After the JSON-driven wizard migration, many core.* NLS keys were deleted from fx-core/resource/package.nls.json and replaced with template.* keys in the templates resource. TypeScript code paths (VS platform, CLI, Add Action flow) still referenced the deleted keys, causing getLocalizedString() to return empty strings — most visibly, the Add Action → MCP option appeared as a blank clickable item.

Changes

• constants.ts — Replace core.createProjectQuestion.mcpForDa.{label,detail} → template.createProjectQuestion.mcpForDa.*; replace 6 RAG source keys → template.teams.rag.source.*; add Platform import; exclude MCP option from ActionStartOptions.all() on VSCode platform
• create.ts — Replace core.*customCopilotRag.placeholder → template.teams.rag.source.placeholder
• CapabilityOptions.ts — Replace 18 core.* keys across CustomEngineAgentOptions, TeamsAgentCapabilityOptions, and CustomCopilotRagOptions with their template.* equivalents
• teamsProjectTypeNode.ts — Replace RAG title and placeholder keys with template.* equivalents
• package.nls.json — Add 4 genuinely missing keys: error.generator.UnknownPolicy, core.createProjectQuestion.option.description.previewOnWindow, core.createProjectQuestion.oneDriveSharePointItem.confirm, driver.typeSpec.compile.description
• question.test.ts — Add ActionStartOptions unit tests covering VSCode/CLI platform behavior and staticAll()

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.00%. Comparing base (3d0c608) to head (e48d7c8).
⚠️ Report is 1 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff            @@
##              dev   #15703    +/-   ##
========================================
  Coverage   92.99%   93.00%            
========================================
  Files         623      623            
  Lines       38538    38540     +2     
  Branches     6973     7137   +164     
========================================
+ Hits        35839    35844     +5     
+ Misses       1959     1957     -2     
+ Partials      740      739     -1     

Files with missing lines	Coverage Δ
packages/fx-core/src/question/constants.ts	77.51% <100.00%> (+2.06%)	⬆️
packages/fx-core/src/question/create.ts	78.04% <ø> (ø)
...ore/src/question/scaffold/vsc/CapabilityOptions.ts	81.69% <ø> (ø)
.../src/question/scaffold/vsc/teamsProjectTypeNode.ts	97.10% <ø> (ø)

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