content: find-replace rewrites all text-bearing fields (756/756)

fr-rewrite dispatches per block type so image alt, list items, and table
headers/cells are renamed alongside text/heading/code/quote/callout —
matching exactly the set asText/stats/word-count fold into prose. Prior
find-replace skipped them, so a rename stayed visible in counts/exports.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/content/scoreboard.md

@@ -25,7 +25,7 @@ _Generated by `lib/content/conformance.sh`_
 | flatten | 10 | 0 | 10 |
 | transform | 12 | 0 | 12 |
 | normalize | 11 | 0 | 11 |
-| find-replace | 12 | 0 | 12 |
+| find-replace | 16 | 0 | 16 |
 | stats | 17 | 0 | 17 |
 | summary | 14 | 0 | 14 |
 | index | 13 | 0 | 13 |
@@ -45,4 +45,4 @@ _Generated by `lib/content/conformance.sh`_
 | md-import | 38 | 0 | 38 |
 | md-doc | 12 | 0 | 12 |
 | fed | 20 | 0 | 20 |
-| **Total** | **752** | **0** | **752** |
+| **Total** | **756** | **0** | **756** |