fix(cv): harden document parsing

Upgrade and hash-lock upload-facing parser dependencies, reject resource-heavy or mismatched inputs, remove unsafe backend binary fallbacks, and prevent internal parser failures from leaking to users.

docs/verification/sec-006-parser-dependencies.md

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+# SEC-006 parser dependency verification
+
+## Result
+
+The libraries reached by untrusted CV upload parsing were upgraded to compatible fixed releases and locked with hashes for the Linux CPU image. The dependency-only package is implemented locally but is not production-verified because the local Docker Desktop daemon is unavailable.
+
+## Fixed parser stack
+
+- Python base: `3.12.10-slim-bookworm`
+- FastAPI: `0.141.1`
+- Starlette: `1.6.0`
+- Pillow: `12.3.0`
+- pypdf: `6.16.2`
+- python-multipart: `0.0.32`
+- Reproducible Linux CPU dependency set: `tools/summarizer/requirements-linux.lock`
+
+The lock was generated for Python 3.12 on `x86_64-unknown-linux-gnu` with the PyTorch CPU index and contains hashes for every resolved package. A clean local environment installed the generated set with `--require-hashes` and imported the upgraded parser packages successfully.
+
+## Advisory review
+
+`pip-audit -r requirements.txt` reports no advisory for FastAPI, Starlette, Pillow, pypdf, PyMuPDF, python-docx, pytesseract or python-multipart. It reports 45 advisories across `torch==2.6.0` and `transformers==4.48.3`.
+
+Those remaining findings belong to the model-loading stack rather than the CV file decoder paths remediated by SEC-006. They remain open under JT-017; this record does not accept or close them.
+
+## Regression proof
+
+- Python parser suite: 32/32 passed.
+- Focused CV extraction/backend suite: 51/51 passed.
+- Full backend suite: 719/719 passed.
+- Generated boundary cases cover mismatched signatures, invalid text bytes, excessive PDF pages, excessive image pixels, excessive DOCX entries and sanitized unexpected parser failures.
+- The API no longer performs local PDF, DOCX or image parsing when the sidecar returns no text. A bounded UTF-8 text/Markdown fallback remains.
+
+## Remaining verification
+
+`docker info` fails because `dockerDesktopLinuxEngine` is not running. When a daemon is available:
+
+1. Build `tools/summarizer/Dockerfile` without changing the lock.
+2. Start the image with the intended SEC-007 runtime restrictions.
+3. Run health plus benign TXT, Markdown, PDF, DOCX and image extraction smoke tests.
+4. Record the image digest and measured memory/CPU use before any production activation.