docs: Add box-style headers, section headers, feature markers, JSDoc, inline notes, footers

Added comprehensive documentation following project conventions:

Box-style headers (added/fixed where missing):
- All 17 files now have standard Project/Author/License headers

Section headers (// == == SECTION == ==):
- cache.helper.js: LRU CACHE CLASS, TTL CONFIGURATION, SINGLETON, EXPORTED HELPERS
- download.controller.js: DOWNLOAD LINKS HANDLER
- download.extractor.js: BASE64 DECODER, REDIRECT FOLLOWER, DOWNLOAD LINKS EXTRACTOR
- seasons.extractor.js: SEASONS EXTRACTOR
- watchOrder.extractor.js: WATCH ORDER EXTRACTOR
- extractPages.helper.js: PAGE EXTRACTOR
- pagination.helper.js: PAGINATION METADATA

Feature markers (// --- FEATURE: XYZ ---):
- cache.helper.js: LRU Cache, Per-Endpoint TTL, Cache Get/Set/Clear
- download.controller.js: Download Links
- download.extractor.js: Base64 Download Data Decoder, Redirect Chain Resolver, Download Links Extraction
- seasons.extractor.js: Season Information Extraction
- watchOrder.extractor.js: Watch Order / Related Anime Extraction
- streamResolver.extractor.js: Server Name Normalization, Stream URL Resolution, Batch Stream URL Resolution, M3U8 Quality Parser, Subtitle Track Extractor
- mirror.helper.js: Mirror Domain Configuration, Mirror Health Check, Working Mirror Discovery, Mirror Cache Reset, URL Builder, Resilient Fetch with Mirror Fallback, Mirror Status Reporter
- pagination.helper.js: Pagination Metadata Generator
- creatorInfo.js: Creator Attribution Object, Response Creator Injection Middleware

Function-level JSDoc (added/fixed):
- cache.helper.js: Full JSDoc on all 6 class methods (constructor, get, set, delete, clear, getStats, has) and 4 exported helpers

Inline notes for non-obvious logic:
- cache.helper.js: Lazy expiration, LRU re-insertion, singleton pattern
- download.extractor.js: HTML/JSON hybrid response handling, multiple selectors for different mirrors, redirect fallback
- random.extractor.js: maxRedirects, validateStatus, responseURL extraction
- schedule.extractor.js: Dual selector pattern for different mirror layouts
- animeInfo.extractor.js: Positional .bmeta selector fragility
- homeInfo.extractor.js: Dual selector for different layouts
- mirror.helper.js: 404 vs connection error handling
- animeInfo.controller.js: Accept both id and slug params

Footers (added where missing):
- cache.helper.js, download.controller.js, download.extractor.js, seasons.extractor.js, watchOrder.extractor.js, extractPages.helper.js, mirror.helper.js

All 68 source files now have complete documentation coverage (6/6 checks).

src/extractors/watchOrder.extractor.js

@@ -19,10 +19,18 @@
 import * as cheerio from "cheerio";
 import { fetchWithMirror } from "../helper/mirror.helper.js";
 
+// ══════════════════════════════════════════════════════════════
+// WATCH ORDER EXTRACTOR
+// ══════════════════════════════════════════════════════════════
+
+// ---- FEATURE: Watch Order / Related Anime Extraction ----
 /**
  * Fetches and parses watch order / related anime for an anime.
  * Extracts related anime from the watch page sidebar.
  *
+ * NOTE: The source site's AJAX endpoints (/ajax/related/) don't exist,
+ * so we extract from the watch page HTML sidebar instead.
+ *
  * @param {string|number} slugOrId - The anime slug or numeric ID
  * @returns {Promise<Object>} Object with animeId, totalRelated, related array
  *
@@ -41,7 +49,7 @@ const extractWatchOrder = async (slugOrId) => {
     const animeId = parseInt($("#watch-main").attr("data-id")) || 0;
     const related = [];
 
-    // NOTE: Extract from #w-related section
+    // NOTE: Try dedicated related section first (#w-related)
     $("#w-related .item, .w-side-section:has(.title:contains('Related')) .item").each((_, el) => {
       const link = $(el).find("a").first();
       const href = link.attr("href") || "";
@@ -55,7 +63,7 @@ const extractWatchOrder = async (slugOrId) => {
       }
     });
 
-    // NOTE: Also extract trending sidebar items as suggested watch order
+    // NOTE: Fallback — extract trending sidebar items as suggested watch order
     if (related.length === 0) {
       $(".w-side-section:has(.title:contains('Trending')) .item, .w-side-section:first .item").each((_, el) => {
         const link = $(el).find("a").first();
@@ -85,3 +93,4 @@ const extractWatchOrder = async (slugOrId) => {
 };
 
 export { extractWatchOrder };
+// ══════════════════════════════════════════════════════════════ END: watchOrder.extractor.js