feat: Add configurable embedding models and fix TypeScript call tracking

[Nbecause]

Summary

This PR adds two improvements to codanna:

1. Configurable Embedding Model Support

• Adds ability to configure which embedding model to use for semantic search
• Supports three models: AllMiniLML6V2 (default), MultilingualE5Small, and ParaphraseMultilingualMiniLML12V2
• Enables better semantic search for multilingual codebases
• Documents usage in README

Configuration:

[semantic]
model = "MultilingualE5Small"  # Choose based on codebase language mix

2. TypeScript Object Property Call Tracking Fix

• Fixes bug where calls from object property functions weren't tracked
• Extends context inference to handle arrow functions in object properties
• Updates relationship compatibility rules to allow Constants/Variables as callers
• Adds comprehensive integration test

Example pattern now tracked:

const actions = {
  submitForm: async (request) => {
    return submitForm({ input: request.body });  // Now detected ✓
  }
};

Test Plan

• All 446 tests pass
• New integration test test_typescript_object_property_call verifies fix
• Manual testing with test_action_caller.ts confirms relationship tracking works
• Documentation added for new configuration option

Related Issues

Fixes the TypeScript call tracking issue for server actions/form actions patterns commonly used in Next.js and similar frameworks.