Add Paper A (IEEE TAI) complete draft with Firm A-calibrated dual-method classification

Paper draft includes all sections (Abstract through Conclusion), 36 references,
and supporting scripts. Key methodology: Cosine similarity + dHash dual-method
verification with thresholds calibrated against known-replication firm (Firm A).

Includes:
- 8 section markdown files (paper_a_*.md)
- Ablation study script (ResNet-50 vs VGG-16 vs EfficientNet-B0)
- Recalibrated classification script (84,386 PDFs, 5-tier system)
- Figure generation and Word export scripts
- Citation renumbering script ([1]-[36])
- Signature analysis pipeline (12 steps)
- YOLO extraction scripts

Three rounds of AI review completed (GPT-5.4, Claude Opus 4.6, Gemini 3 Pro).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

paper/paper_a_impact_statement.md

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+# Impact Statement
+
+<!-- 100-150 words. Non-specialist readable. No jargon. Specific, not vague. -->
+
+Auditor signatures on financial reports are a key safeguard of corporate accountability.
+When Certified Public Accountants digitally copy and paste a single signature image across multiple reports instead of signing each one individually, this safeguard is undermined---yet detecting such practices through manual inspection is infeasible at the scale of modern financial markets.
+We developed an artificial intelligence system that automatically extracts and analyzes signatures from over 90,000 audit reports spanning over a decade of filings by publicly listed companies.
+By combining deep learning-based visual feature analysis with perceptual hashing, the system distinguishes genuinely handwritten signatures from digitally replicated ones.
+Our analysis reveals substantial variation in signature similarity patterns across accounting firms, with a calibration group independently identified as using digital replication exhibiting distinctly higher similarity scores.
+After further validation, this technology could serve as an automated screening tool to support financial regulators in monitoring signature authenticity at national scale.