blogimport: Q-M4 live source — internal-data query adapter (75/75)

source.sx: live-source adapter resolving Q-M4 (internal-data query, not direct PG).
Injected fetch-fn transport port (hexagonal seam); parse-row maps a blog post-row to
the importer post dict and parses the :lexical JSON string via dream-json-parse.
End-to-end drivers: backfill! (enumerate->fetch->import) and sync-verify
(enumerate->fetch->verify), + backfill-ids! explicit-id fallback.

Tests mock the transport against the documented response contract incl. a real lexical
JSON string. README flags the one blog-side gap (add a published-posts enumeration
query) + production fetch_data wiring (lives in lib/host). source 20/20; total 75/75.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/blogimport/scoreboard.md

@@ -7,4 +7,5 @@ _Generated by `lib/blogimport/conformance.sh`_
 | lexical | 23 | 0 | 23 |
 | import | 21 | 0 | 21 |
 | verify | 11 | 0 | 11 |
-| **Total** | **55** | **0** | **55** |
+| source | 20 | 0 | 20 |
+| **Total** | **75** | **0** | **75** |