feat: Nerd Font support, clipboard paste, and PTY environment fixes

- Add ttyd-nerd-font submodule with embedded JetBrains Mono Nerd Font
  for proper icon rendering in browser via ttyd
- Add Ctrl+Shift+V / Shift+Insert paste support in ttyd frontend
- Strip Zellij env vars from PTY child processes to prevent workspace
  terminal from inheriting Zellij session context
- Launch PTY commands through login shell for proper PATH resolution
- Use /etc/passwd shell lookup instead of $SHELL (Zellij overrides it)
- Soften ANSI 256-color palette to match modern dark themes
- Handle Nerd Font PUA glyphs as width 1 in pyte terminal emulator
- Fix brightmagenta typo in pyte graphics
- Update install script to build ttyd from submodule source
- Add web deployment TODO items for image paste and context menu

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

TODO.md

@@ -110,6 +110,11 @@ Long-term open items for Clide development.
 - [ ] Plugin development guide
 - [ ] Architecture documentation updates
 
+## Web Deployment (ttyd)
+
+- [ ] Image paste support: intercept browser clipboard image on Ctrl+V, upload blob to server, save as temp file. Claude Code already handles Ctrl+V as image paste — just needs the image on the filesystem
+- [ ] Right-click context menu for copy/paste in web terminal
+
 ## Build & Distribution
 
 - [ ] PyInstaller builds for macOS