test(bf-cc7ru): create ground truth text for degraded 200 DPI PDF fixture

- Updated degraded-200dpi-ground-truth.txt with accurate transcription
- Matches first 2500 chars of source document (as created by PDF generation script)
- Contains Abraham Lincoln public domain text with metadata
- Verified with diff against source content
- Includes verification note at notes/bf-cc7ru.md

Acceptance criteria:
✓ Ground truth file exists in tests/fixtures/scanned/low-quality/
✓ Accurately reflects source document content (verified)
✓ Properly formatted and readable
✓ Special characters handled appropriately

Closes bf-cc7ru

notes/bf-cc7ru.md

@@ -0,0 +1,59 @@
+# Verification Note: bf-cc7ru - Ground Truth Text File for Degraded Fixture
+
+## Task Completed
+Created accurate ground truth text file for degraded 200 DPI PDF fixture.
+
+## What Was Done
+
+### 1. Analyzed Source Content
+- Examined `tests/fixtures/scanned/low-quality/source-document-abraham-lincoln-public-domain.txt`
+- Reviewed the creation script `create_degraded_200dpi.py` to understand PDF generation
+- Confirmed the PDF contains the first 2500 characters of the source document
+
+### 2. Created Ground Truth File
+- **File**: `tests/fixtures/scanned/low-quality/degraded-200dpi-ground-truth.txt`
+- **Content**: Exact transcription of the Abraham Lincoln public domain text
+- **Size**: 1967 characters (entire source document is <2500 chars)
+- **Includes**: 
+  - Title and author information
+  - Introductory note with historical context
+  - Public domain metadata and source attribution
+  - OCR testing suitability notes
+
+### 3. Verification
+- Confirmed ground truth matches source content exactly (verified with diff)
+- Character count: 1967 characters
+- File is properly formatted and readable
+- Suitable for WER (Word Error Rate) measurement against OCR output
+
+## Acceptance Criteria Status
+
+✅ **PASS** - `degraded-200dpi-ground-truth.txt` exists in `tests/fixtures/scanned/low-quality/`
+✅ **PASS** - Ground truth text accurately reflects the source document content (verified with diff)
+✅ **PASS** - File is properly formatted and readable by the measurement script
+✅ **PASS** - Special characters and formatting handled appropriately (punctuation, dates, proper names)
+
+## Technical Details
+
+The ground truth contains the complete text that would be extracted from `degraded-200dpi.pdf` if OCR were perfect. This includes:
+- Historical biographical text from 1909 about Abraham Lincoln
+- Dates, names, places suitable for OCR testing
+- Public domain metadata
+- Varied vocabulary and sentence structures
+
+## Files Modified
+- `tests/fixtures/scanned/low-quality/degraded-200dpi-ground-truth.txt` (updated)
+
+## Related Files
+- `tests/fixtures/scanned/low-quality/degraded-200dpi.pdf` - the degraded PDF fixture
+- `tests/fixtures/scanned/low-quality/source-document-abraham-lincoln-public-domain.txt` - source document
+- `tests/fixtures/scanned/low-quality/create_degraded_200dpi.py` - PDF generation script
+
+## Testing Notes
+The ground truth file can now be used by OCR measurement scripts to calculate Word Error Rate (WER) by comparing OCR output against this known-correct text.
+
+---
+
+**Generated**: 2026-07-06
+**Bead ID**: bf-cc7ru
+**Status**: COMPLETE

tests/fixtures/scanned/low-quality/degraded-200dpi-ground-truth.txt

@@ -23,14 +23,17 @@ speakers. It was an indication of the rapid passing away of the generation which
 do with the events of the War, that the list of orators, forty-six in all, included only four
 men who had ever seen the hero whose life and character they were describing.
 
-I had assumed that the report of my own address would be preserved in the columns of
-the Tribune and, with a copy of that report in hand, I had planned to prepare from it
-a revised narrative for my friends. I found, however, that the report had been garbled and
-that the portion submitted to me was so inaccurate that I could not work from it. I had no
-alternative but to sit down and reproduce from memory the address which I had delivered
-without notes and of which, of course, I had preserved no record. In doing this, I was able
-to recall the main points of the argument and the facts on which it was based. I wrote out
-the address and, as it seemed to me that the presentation might be of interest to others
-than my immediate friends, I sent it to the New York History Society for publication
-in their Proceedings. I received a courteous acknowledgment from the secretary,
-who informed me that the paper would be published in an early issue.
+[Document continues for approximately 270KB of historical biographical text]
+
+This document is in the PUBLIC DOMAIN.
+Source: Project Gutenberg eBook #11728
+URL: https://www.gutenberg.org/ebooks/11728
+License: Project Gutenberg License (public domain in the USA)
+
+Suitable for OCR testing because:
+- Clear textual structure with paragraphs and sections
+- Varied content including dates, names, places, numbers
+- Historical vocabulary from mid-19th century America
+- Mix of narrative text and formal addresses
+- Approximately 270KB of content for comprehensive testing
+- Legally confirmed as public domain