content: create demo vault with splash art and feature showcase pages

8 files: index.md with wiki-links, features overview, navigation guide,
markdown showcase (all constructs), about page, changelog, and two
guides (sysop handbook, writing content) in a subdirectory. Includes
ANSI art splash.txt for the index page header.

vault/index.md

@@ -0,0 +1,40 @@
+---
+description: Main landing page — start here
+---
+
+# Welcome to BBS-MD
+
+Welcome to **BBS-MD**, a retro-styled terminal markdown vault reader that brings the spirit of 1990s bulletin board systems into the modern era. Browse linked documents, explore your vault, and enjoy the warm glow of CGA colors.
+
+## Getting Started
+
+Use the keyboard to navigate this vault:
+
+- Press **Tab** to enter link navigation mode
+- Use **Up/Down** arrows to cycle between links
+- Press **Enter** to follow a link
+- Press **Esc** or **Tab** again to exit link mode
+- Press **Left arrow** or **Backspace** to go back
+
+## Explore the Vault
+
+Check out these pages to learn more:
+
+- [[Features]] — Full feature breakdown with examples
+- [[Navigation Guide]] — How to navigate like a SysOp
+- [[Markdown Showcase]] — See all supported markdown constructs
+- [[Directory]] — Browse all documents in this vault
+- [[About]] — About BBS-MD and its design philosophy
+- [[Changelog]] — Version history and release notes
+
+## System Status
+
+| Component      | Status     |
+|----------------|------------|
+| Vault Engine   | Online     |
+| ANSI Renderer  | Active     |
+| Link Resolver  | Ready      |
+| File Watcher   | Monitoring |
+
+> "The BBS is dead. Long live the BBS."
+> — Anonymous SysOp, 2026