Added PDF text and table extraction actions:

• Find Text Position - Returns coordinate positions of text occurrences within a PDF document
• Extract Structured Text - Returns all text items with position coordinates, dimensions, and font metadata for custom parsing
• Extract Text with Layout - Preserves line breaks and paragraph spacing from the original PDF layout
• Extract Table Data - Detects and extracts tabular structures as two-dimensional arrays using coordinate-based heuristics

Improved error handling across PDF processing actions with descriptive error messages and detection of corrupted or invalid PDF structures