feat(v2): restore in-page search/tag filter & drop redundant Markdown TOC

Fix: the per-page resource search box with maturity tag-pills stopped
appearing after navigation.instant was enabled (DOMContentLoaded fires only
on first SPA load). Reworked v2_filter.js to init via Material's document$
observable with a DOMContentLoaded fallback, guard double-injection, bind the
clickable-tag delegation once, and add a no-results state. Cache-bust ?v=2.9.12.

Change: removed the duplicated Markdown "## Table of Contents" from all 156 V2
content pages and from v2_optimizer.py — it forced hundreds of links of scroll
on large pages. Replaced by Material's native sticky "On this page" TOC
(removed toc.integrate, added toc.follow). tags.md keeps its TOC (it is an index).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

v2-docs/java_app_servers.md

@@ -6,24 +6,6 @@
 !!! info "Architectural Context"
     Detailed reference for Server Vendors Providing Java EE/Jakarta EE and MicroProfile Runtimes in the context of Developer Ecosystem.
 
-## Table of Contents
-
-1. [Cloud-Native Java](#cloud-native-java)
-  - [Runtimes](#runtimes)
-    - [JBoss EAP](#jboss-eap)
-      - [MicroProfile](#microprofile)
-    - [Payara Micro](#payara-micro)
-      - [Docker](#docker)
-    - [Payara Server](#payara-server)
-      - [Docker](#docker-1)
-    - [WildFly](#wildfly)
-      - [Developer Workflow](#developer-workflow)
-1. [Enterprise Java](#enterprise-java)
-  - [Runtimes](#runtimes-1)
-    - [Apache TomEE](#apache-tomee)
-    - [KumuluzEE](#kumuluzee)
-    - [Payara Server](#payara-server-1)
-
 ## Cloud-Native Java
 
 ### Runtimes