fix: add configSchema to openclaw.plugin.json, add search CLI command, fix total_docs stat

- Add required configSchema to openclaw.plugin.json for OpenClaw plugin discovery
- Add search command to CLI with --limit, --dir, --from-date, --to-date, --tags filters
- Fix get_stats() to properly count unique docs (was returning 0 for non-null values)
- Remove hardcoded max_results default of 5; search now returns all results by default
- Update INSTALL.md and design docs with correct OpenClaw extension path instructions

src/utils/lancedb.ts

@@ -74,7 +74,7 @@ export async function searchVectorDb(
   }
   const whereClause = conditions.length > 0 ? conditions.join(" AND ") : undefined;
 
-  const limit = options.max_results ?? 5;
+  const limit = options.max_results;
 
   // Try vector search first; if Ollama is down embedQuery throws → fallback to FTS
   let rows: Record<string, unknown>[];
@@ -85,14 +85,20 @@ export async function searchVectorDb(
     if (whereClause) {
       queryBuilder = queryBuilder.filter(whereClause);
     }
-    rows = await queryBuilder.limit(limit).toArray();
+    if (limit !== undefined) {
+      queryBuilder = queryBuilder.limit(limit);
+    }
+    rows = await queryBuilder.toArray();
   } catch {
     // Ollama unavailable — fallback to full-text search on chunk_text (BM25 scoring)
     let ftsBuilder = table.query().fullTextSearch(query);
     if (whereClause) {
       ftsBuilder = ftsBuilder.filter(whereClause);
     }
-    rows = await ftsBuilder.limit(limit).toArray();
+    if (limit !== undefined) {
+      ftsBuilder = ftsBuilder.limit(limit);
+    }
+    rows = await ftsBuilder.toArray();
   }
 
   return rows.map((r: Record<string, unknown>) => ({