… and --bundler option

Add Bundler type alias, CompilerInterface and CompilerAsset to the
shared types.ts. Remove duplicate CompilerAsset definitions from
rspack/types.ts and webpack/types.ts. Add --bundler <string> CLI
option to both startCommandOptions and bundleCommandOptions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Add detectBundler() utility that determines the bundler engine with
the following priority:
1. Explicit --bundler flag
2. Custom config path filename inference (rspack.* vs webpack.*)
3. Config file discovery (rspack configs checked first)
4. Default: rspack

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Webpack Compiler:
- Remove EventEmitter inheritance
- Add platforms property and devServerContext with late-init
- Add setDevServerContext() and start() (no-op) methods
- Internalize event handling: worker messages now call
  devServerContext.notifyBuildStart/End and broadcastToHmrClients
  directly instead of emitting events
- Constructor now takes platforms as first argument

Rspack Compiler:
- Add 'implements CompilerInterface' declaration
- Import CompilerAsset from shared types

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

…ction

Add unified bundle.ts and start.ts that merge the rspack and webpack
implementations, using detectBundler() and dynamic imports to select
the correct engine at runtime.

Add commands/index.ts exporting the unified command definitions and
a createBoundCommands() helper for deprecated entry points.

Add commands/index.js and commands/index.d.ts as the new primary
CJS entry point. Update commands/rspack.js and commands/webpack.js
to be deprecation wrappers that delegate via createBoundCommands().

Add './commands' export to package.json (alongside existing wildcard).

Delete old bundler-specific files:
- rspack/bundle.ts, rspack/start.ts, rspack/index.ts
- webpack/bundle.ts, webpack/start.ts, webpack/index.ts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Update init package:
- Remove bundler parameter from modifyReactNativeConfig()
- Use '@callstack/repack/commands' instead of bundler-specific paths

Simplify react-native.config.js in all test apps to use the unified
import instead of conditional require based on USE_WEBPACK env var.

Update integration tests to import from '@callstack/repack/commands'
instead of separate rspack/webpack command sets.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>