Fix PHP file language detection to enable specialized transformer

[Copilot]

The PHP transformer (_transform_php_code) was never executed because .php files weren't tagged with language metadata during file processing.

Changes

• Added .php to the file extension list in extract_file_metadata() (services/pipeline/base.py:180)

This enables PHP files to be routed to the specialized transformer instead of falling through to the generic code handler. The language mapping .php → "php" already existed in get_language_from_extension().

# Before: PHP files got language="unknown", used generic transformer
if path.suffix in ['.py', '.js', '.ts', '.java', '.cpp', '.c', '.h', '.cs', '.go', '.rs']:
    metadata["language"] = get_language_from_extension(path.suffix)

# After: PHP files get language="php", use _transform_php_code
if path.suffix in ['.py', '.js', '.ts', '.java', '.cpp', '.c', '.h', '.cs', '.go', '.rs', '.php']:
    metadata["language"] = get_language_from_extension(path.suffix)

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[Copilot]

Pull Request Overview

This PR fixes a bug where PHP files were not being routed to the specialized PHP transformer (_transform_php_code) because they lacked language metadata during file processing. The fix adds .php to the file extension check in extract_file_metadata(), enabling proper language detection for PHP files.

Key Changes:

• Added .php extension to the file type check in extract_file_metadata() to enable language metadata assignment for PHP files

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