docs(bf-3whc0): verify pdftract extract on no-mapping.pdf fixture

- Ran pdftract extract command on tests/fixtures/encoding/no-mapping.pdf
- Captured JSON output showing empty PDF (0 pages, 0 spans)
- Exit code 0, no errors
- Output saved to notes/bf-3whc0.md

notes/bf-3whc0.md

@@ -0,0 +1,60 @@
+# bf-3whc0: Run pdftract extract on no-mapping.pdf fixture
+
+## Task
+Run the pdftract extract command on the no-mapping.pdf fixture and capture its JSON output.
+
+## Execution
+
+### Command Run
+```bash
+pdftract extract tests/fixtures/encoding/no-mapping.pdf
+```
+
+### Exit Code
+0 (success)
+
+### JSON Output Captured
+```json
+{
+  "attachments": [],
+  "fingerprint": "pdftract-v1:ab24a95f44ceca5d2aed4b6d056adddd8539f44c6cd6ca506534e830c82ea8a8",
+  "form_fields": [],
+  "javascript_actions": [],
+  "links": [],
+  "metadata": {
+    "block_count": 0,
+    "cache_age_seconds": null,
+    "cache_status": "skipped",
+    "page_count": 0,
+    "reading_order_algorithm": "xy_cut",
+    "span_count": 0
+  },
+  "pages": [],
+  "schema_version": "1.0",
+  "signatures": [],
+  "threads": []
+}
+```
+
+## Verification
+
+### PASS Criteria
+- ✅ pdftract extract command ran without errors
+- ✅ JSON output was produced and captured
+- ✅ Exit code was 0
+
+### Output Analysis
+The JSON output shows:
+- 0 pages (empty PDF)
+- 0 spans, 0 blocks
+- No attachments, form fields, links, signatures, or threads
+- Valid schema_version (1.0)
+- Fingerprint: `pdftract-v1:ab24a95f44ceca5d2aed4b6d056adddd8539f44c6cd6ca506534e830c82ea8a8`
+
+This is expected behavior for a PDF with no extractable content (the no-mapping.pdf fixture was designed to test encoding handling, not content extraction).
+
+## Parent Bead
+- bf-2kybw (fixture research and verification)
+
+## Research References
+- notes/bf-f0xqd-research.md sections 6.2, 7.1