fix: add TypeScript path mapping for workspace packages in development mode

[Haadka]

Problem

On Windows 11, @opencode-ai/sdk package could not be resolved when running bun dev, causing the error:

error: Cannot find module '@opencode-ai/sdk' from 'packages/opencode/src/plugin/index.ts'

Solution

Added TypeScript path mapping to packages/opencode/tsconfig.json:

• Added baseUrl and paths configuration
• Maps @opencode-ai/sdk and @opencode-ai/plugin to their source TypeScript files
• Only affects development mode with --conditions=development
• Production builds continue to use the proper workspace package resolution

Testing

• ✅ bun dev now starts successfully
• ✅ Module imports resolve correctly in development
• ✅ Production builds unaffected (uses dist/ files via package.json exports)
• ✅ All typecheck tests pass

Changes

• Modified packages/opencode/tsconfig.json to include path mapping for workspace packages
• This is a development-only fix that maintains proper package abstractions

[thdxr]

curious why --conditions=development doesn't work?