Improve template exceptions with original source mapping across extends

[Copilot]

Template errors were surfacing from merged/compiled output, making it hard to locate the real fault—especially when the bug lived in a parent layout (extends). This change makes syntax/parser failures report the original template file, line, and column where the error actually exists.

• Source-aware inheritance merge

  • Added source-map preservation while resolving extends and block overrides.
  • Kept character-level origin metadata through parent/child composition so downstream stages can attribute failures to the correct file.

• Lexer-level source metadata

  • Lexer::tokenize() now accepts optional source mapping and annotates tokens with:
    • source_file
    • source_line
    • source_column
  • Lexer syntax failures now emit location-aware SyntaxException messages with contextual snippet.

• Stronger syntax exception model

  • Refactored SyntaxException to support structured location/context construction (fromLocation(...)).
  • Renderer now raises syntax errors via location-aware construction for consistent error shape.

• Parser exceptions with exact origin

  • Parser errors now include template-origin coordinates from token metadata.
  • Unclosed control-tag errors now report where the opening tag was declared (including parent layout files), not only parser cursor state.

• Clearer extends-chain failures

  • Improved parent-missing/circular-extends messages to include both referenced parent and referencing template path for faster traceability.

• Docs

  • Updated README to state that extends-driven errors now point to the original template source location.

throw SyntaxException::fromLocation(
    $templateFile,
    $line,
    $column,
    $snippet,
    $details
);