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-sql/expected-bundle/index.md

@@ -0,0 +1,2 @@
+Golden sql-source bundle: metrics extracted from a sqlite fixture database.
+- [Metrics](ingest-metrics.md)

examples/ingest-golden-sql/expected-bundle/ingest-metrics.md

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+---
+type: dataset
+title: Metrics
+source_system: golden-db
+source_query: SELECT id, name, value, comment FROM metrics ORDER BY id
+ingested_at: 2026-07-16T12:00:00Z
+ingest_manifest: manifest@93a04cce66d99b53
+generated: true
+---
+
+| id | name | value | comment |
+| --- | --- | --- | --- |
+| 1 | throughput | 12.5 | steady\|rate |
+| 2 | latency | 0.1 |  |
+| 3 | errors | 3.0 |  |