feat(fiction-assistance): register plugin with full bespoke command set

Snapshot of the fiction-assistance plugin in its original Universalis-
specific form before generalization. Adds the missing plugin.json
manifest (subdirectory command paths explicitly listed), moves the two
stray root-level review files into their proper homes (review-all.md
into the reviewing-fiction skill, review-final.md as a command with
frontmatter), and registers the plugin in the marketplace.

Preserved here so the original card-generation and vault-maintenance
commands remain recoverable when the plugin is reduced to a portable
guidance-and-analysis subset in the next commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.claude-plugin/marketplace.json

@@ -24,6 +24,11 @@
       "name": "symphony",
       "source": "./symphony",
       "description": "Tracker-agnostic orchestrator daemon — polls the issue tracker, dispatches isolated worker agents per issue, reconciles state. Pairs with composer."
+    },
+    {
+      "name": "fiction-assistance",
+      "source": "./fiction-assistance",
+      "description": "Fiction writing tools — scene analysis, character cards, continuity checks, story statistics, developmental and strategic review. Built around an Obsidian-based novel workspace."
     }
   ]
 }