docs(pdftract-145s8): update SDK docs with correct API

- Update SDK README.md from draft placeholder to proper content
- Fix rust.md examples to use correct SDK contract functions:
  - extract_pdf -> extract (SDK contract)
  - extract_pdf_streaming -> extract_stream (SDK contract)
  - Remove OutputOptions parameter (not in SDK API)
- Add proper type hints and Path::new for URLs
- Add sample.pdf fixture with provenance entry
- Verify mdBook renders correctly
- Verify cross-references work (MCP, JSON schema, CLI, OCR)

tests/fixtures/profiles/PROVENANCE.md

@@ -279,4 +279,5 @@ bash scripts/check-provenance.sh
 | profiles/book_chapter/technical_manual_chapter.pdf | tests/fixtures/generate_book_chapter_fixtures.rs | MIT-0 | 2026-05-27 | ac51b60fa78d4d65f5d4970a41037113750d99c9619ed3df5d60932049089845 | Technical manual chapter - synthetic test data |
 | profiles/book_chapter/textbook_chapter.pdf | tests/fixtures/generate_book_chapter_fixtures.rs | MIT-0 | 2026-05-27 | d5ca8b57fc58397c3e1549fb1ab0532b651b4aaeadeddab2766fe7b419ba5a07 | Textbook chapter - synthetic test data |
 | remote_100page.pdf | tests/fixtures/generate_large_remote_fixture.rs | MIT-0 | 2026-05-29 | 16bcbee828006e51a125e7fe8e53be11ccd504b6b7e572f8ab26ee2c5c0b36e7 | Synthetic 100-page PDF for remote source range-request testing |
+| sample.pdf | tests/fixtures/valid-minimal.pdf (copied) | MIT-0 | 2026-05-31 | 34dabcd045665fff5dc2b2e2930905c23226704b4bc318f0ec08344be889e447 | Minimal valid PDF v1.4 fixture for SDK example default path |
 | security/sensitive.pdf | tests/fixtures/security/generate_sensitive_fixture.py | MIT-0 | 2026-05-29 | ba3ca8228cf835a6bc334acd8e084b32489af1a300d38b461f9db2382cbd48c6 | Synthetic password-protected PDF with unique markers for TH-08 log audit testing |

tests/fixtures/sample.pdf

@@ -0,0 +1,58 @@
+%PDF-1.4
+1 0 obj
+<<
+/Type /Catalog
+/Pages 2 0 R
+>>
+endobj
+2 0 obj
+<<
+/Type /Pages
+/Kids [3 0 R]
+/Count 1
+>>
+endobj
+3 0 obj
+<<
+/Type /Page
+/Parent 2 0 R
+/MediaBox [0 0 612 792]
+/Contents 4 0 R
+/Resources <<
+/Font <<
+/F1 <<
+/Type /Font
+/Subtype /Type1
+/BaseFont /Helvetica
+>>
+>>
+>>
+>>
+endobj
+4 0 obj
+<<
+/Length 44
+>>
+stream
+BT
+/F1 12 Tf
+100 700 Td
+(Test) Tj
+ET
+endstream
+endobj
+xref
+0 5
+0000000000 65535 f
+0000000009 00000 n
+0000000058 00000 n
+0000000115 00000 n
+0000000298 00000 n
+trailer
+<<
+/Size 5
+/Root 1 0 R
+>>
+startxref
+403
+%%EOF