feat(cli): improve guide file placement and handling in sync script

apps/cli/sync.ts

@@ -22,7 +22,10 @@
  *   `apps/docs/topic-landings.ts`) gets a placeholder guide page,
  *   `guides/<slug>.mdx`, with `list:` pointing at LeetCode's problem list for
  *   the tag. Created once (a missing or empty file), then hand-owned; the tag's
- *   badge on a problem page links to it.
+ *   badge on a problem page links to it. A guide may be filed into a category
+ *   `(group)` folder (e.g. `guides/(2-algorithms)/`) — no route segment, so
+ *   `/guides/<slug>` holds — and is found there by slug; a new placeholder
+ *   lands at the `guides/` root for a human to file.
  *
  * The sidebar group is the campaign TOPIC from the README table (`tree-dfs/`,
  * ordered by topic number via a script-owned `meta.ts`). A problem outside the
@@ -723,16 +726,21 @@ for (const sol of ordered) {
 }
 
 // One guide page per tag that no campaign topic teaches, created when missing
-// (an empty file counts as missing) and never rewritten. A guide whose tag no
+// (an empty file counts as missing) and never rewritten. A guide is found by
-// page carries any more is left alone: it is hand-owned.
+// slug anywhere under guides/ — a human files it into a category `(group)`,
+// which leaves its route alone — and a new one lands at the guides/ root. A
+// guide whose tag no page carries any more is left alone: it is hand-owned.
 const guideTags = [...tags.values()]
   .filter((tag) => !TOPIC_LANDINGS[tag.slug])
   .sort((a, b) => a.slug.localeCompare(b.slug));
+const guideFiles = new Map<string, string>(); // slug -> path relative to DOCS
+for await (const rel of new Bun.Glob("guides/**/*.mdx").scan(DOCS)) guideFiles.set(basename(rel, ".mdx"), rel);
 for (const tag of guideTags) {
-  const file = Bun.file(join(DOCS, "guides", `${tag.slug}.mdx`));
+  const rel = guideFiles.get(tag.slug) ?? `guides/${tag.slug}.mdx`;
+  const file = Bun.file(join(DOCS, rel));
   if ((await file.exists()) && file.size > 0) continue;
   await Bun.write(file, guidePage(tag));
-  report.push([`tag ${tag.slug}`, `guides/${tag.slug}.mdx`, "created"]);
+  report.push([`tag ${tag.slug}`, rel, "created"]);
 }
 
 // Phase metas: created when missing (an empty file counts as missing), never