feat(examples): ship the §11 golden fixtures with byte-exact conformance

TDD step 8: three golden cases per the §11 format (manifest.json,
fixture/, ingested-at.txt, expected-bundle/) — ingest-golden-file and
ingest-golden-sql are the conformance MUSTs; ingest-golden-http
documents and exercises the optional extension against mock payloads.
The conformance test re-materializes each case into a fresh directory
and compares byte for byte; offline and credential-free (the sql
fixture is a committed database file, http never opens a socket).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QeqhJpYQyghASjiJo5EhGg

examples/ingest-golden-file/expected-bundle/index.md

@@ -0,0 +1,3 @@
+Golden file-source bundle: orders and products extracted from a CSV catalogue.
+- [Orders](ingest-orders.md)
+- [Products](ingest-products.md)

examples/ingest-golden-file/expected-bundle/ingest-orders.md

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+---
+type: dataset
+title: Orders
+source_system: golden-catalogue
+source_query: orders.csv
+ingested_at: 2026-07-16T12:00:00Z
+ingest_manifest: manifest@37674ac20059e788
+generated: true
+---
+
+| order_id | customer | total |
+| --- | --- | --- |
+| 1001 | Alice | 250.5 |
+| 1002 | Bob | 99.9 |
+| 1003 | Carol | 0.1 |

examples/ingest-golden-file/expected-bundle/ingest-products.md

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+---
+type: dataset
+title: Products
+source_system: golden-catalogue
+source_query: products.csv
+ingested_at: 2026-07-16T12:00:00Z
+ingest_manifest: manifest@37674ac20059e788
+generated: true
+---
+
+| sku | name | note |
+| --- | --- | --- |
+| A-1 | Pipe\|Product | has\|pipe |
+| B-2 | Back\\slash | line1 line2 |
+| C-3 | Plain |  |