refactor(cli): centralize content registry building

Extract buildRegistryFromIndex and normalizePathKey from the CLI serve
command and the browser completions module into the shared
content-registry module. This ensures both paths produce identical
pathIndex/docContent, including the spark-injection pass that was
previously only applied in the CLI.

src/components/journal/completions.ts

@@ -16,7 +16,7 @@ import {
   setInlineResolver,
 } from "../../data-loader/file-index";
 import {
-  scanDoc,
+  buildRegistryFromIndex,
   deriveCompletions,
   resolveInlineByPath,
   type ContentRegistry,
@@ -108,19 +108,16 @@ async function tryServerRegistry(): Promise<void> {
 async function scanClientSide(): Promise<JournalCompletions> {
   const paths = await getPathsByExtension("md");
 
-  // Build a registry from the in-memory file index, then derive completions
-  // through the same shared pipeline as the CLI.
-  const registry: ContentRegistry = { pathIndex: {}, docContent: {} };
-
-  // First pass: load all .md content into the registry.
+  // Load all .md content into a raw index, then build the registry through
+  // the same shared pipeline as the CLI (scanDoc + spark injection).
+  const index: Record<string, string> = {};
   for (const filePath of paths) {
     const content = await getIndexedData(filePath);
     if (!content) continue;
-    const result = scanDoc(content, filePath);
-    registry.pathIndex[filePath] = result.stripped;
-    registry.docContent[filePath] = result.content;
+    index[filePath] = content;
   }
 
+  const registry = buildRegistryFromIndex(index);
   activeRegistry = registry;
   return deriveCompletions(registry);
 }