docs: restore hero banner with ECC wordmark, v2.0.0 badge, and brand lettermark

Recreates the v1.10 hero banner design (sourced from commit 602894ef)
that PR #2225 replaced with a plain HTML header:

- Wordmark and breadcrumb now read ECC / affaan-m/ECC
- Version badge reads v2.0.0 · Jun 2026, eyebrow updated to V2.0
- Top-left mark is the actual assets/ecc-icon.svg lettermark (amber E,
  coral CC) instead of a generic coral square
- Catalog columns refreshed with live counts (261 skills, 64 agents,
  84 commands, 409 catalog) and real item names from the repo
- Harness pills updated to the current README list (Claude Code, Codex,
  Cursor, OpenCode, Gemini, Zed, Copilot)
- SVG source committed as assets/hero.svg so future edits never need
  image archaeology; rendered to PNG at 2400x1350 via sharp

README hero line restored to the markdown image; badges, sponsor table,
and guide cards from #2225 kept intact.

README.md

@@ -1,14 +1,6 @@
 **Language:** English | [Português (Brasil)](docs/pt-BR/README.md) | [简体中文](README.zh-CN.md) | [繁體中文](docs/zh-TW/README.md) | [日本語](docs/ja-JP/README.md) | [한국어](docs/ko-KR/README.md) | [Türkçe](docs/tr/README.md) | [Русский](docs/ru/README.md) | [Tiếng Việt](docs/vi-VN/README.md) | [ไทย](docs/th/README.md) | [Deutsch](docs/de-DE/README.md) | [Español](docs/es/README.md)
 
-<div align="center">
-
-<a href="https://ecc.tools"><img src="assets/ecc-icon.svg" width="120" alt="ECC logo" /></a>
-
-<h1>ECC</h1>
-
-<p><strong>The harness-native operator system for agentic work.</strong></p>
-
-</div>
+![ECC — the agent harness operating system](assets/hero.png)
 
 [![Stars](https://img.shields.io/github/stars/affaan-m/ECC?style=flat)](https://github.com/affaan-m/ECC/stargazers)
 [![Forks](https://img.shields.io/github/forks/affaan-m/ECC?style=flat)](https://github.com/affaan-m/ECC/network/members)