feat: implement comprehensive Ktor multiline routing support

[zerochae]

PR 내용

Summary

• ✅ Add complete multiline routing pattern detection and parsing for Ktor
• ✅ Support nested route() base paths with multiline definitions
• ✅ Implement end_line_number for proper multiline highlighting
• ✅ Fix root path handling bug in Parser.combine_paths() method

Changes Made

Core Parser Improvements

• Fixed combine_paths() method to properly handle root paths ("/" + "/" = "/")
• Added special case handling for root endpoint combinations

Ktor Parser Enhancements

• Multiline routing detection: _is_multiline_routing() identifies patterns like get(
• Multiline path extraction: _extract_path_multiline() reads across multiple lines to find full routing definition
• Multiline base path support: Enhanced _extract_base_paths_from_file() to handle multiline route() declarations
• End-to-end highlighting: Added end_line_number support for complete multiline highlighting

Complex Pattern Support

Now supports complex multiline patterns like:

route(
  "/api/multiline"
){
  get(
    "/users/{id}"
  ) {
    // handler code
  }
}

Type Safety

• Updated meta/types.lua with new method signatures
• Added proper type annotations for multiline functions

Test Results

• ✅ Multiline endpoints properly detected: GET /api/multiline/users/{id}
• ✅ Base paths correctly combined from nested route() blocks
• ✅ Full range highlighting (lines 17-19) working in previewers
• ✅ Root path edge cases fixed: GET / instead of GET (empty)

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