Correct #platform subpath mappings in generated package metadata and emitted helper imports

[Copilot]

Generated Azure monorepo package metadata was emitting #platform imports with .js-suffixed keys/targets, while emitted helper imports also used .js suffixes that do not match the intended subpath pattern. This updates both metadata generation and emitted/import-rewritten specifiers to use extensionless #platform/* subpaths with source .ts/.mts targets.

• Package.json imports generation (rlc-common)

  • Switched subpath key from #platform/*.js to #platform/*.
  • Updated source targets to TypeScript sources:
    • browser: ./src/*-browser.mts
    • react-native: ./src/*-react-native.mts
    • default: ./src/*.ts
  • Applied in both initial package generation and package update/migration paths.

• Emitter subpath import specifiers (typespec-ts)

  • Removed .js suffix from generated #platform/... helper imports in binder logic.
  • Updated static-helper import rewrite for platform-types to emit #platform/static-helpers/platform-types (no extension).

• Focused coverage updates

  • Expanded package metadata tests to assert exact imports shape for default and react-native variants.
  • Added integration assertions that binder/static-helper rewriting emits extensionless #platform/... specifiers.

{
  "imports": {
    "#platform/*": {
      "browser": "./src/*-browser.mts",
      "react-native": "./src/*-react-native.mts",
      "default": "./src/*.ts"
    }
  }
}

import { getBinaryResponse } from "#platform/static-helpers/serialization/get-binary-response";