feat(web): install.sh and InstallToggle use one-command UX

- /install shell script now points users at `claudemesh <invite-url>`
  (one step) instead of the split join+launch
- InstallToggle first-time panel shows single copy-block with
  install+launch on the same line
- Also advertises url-handler install and shell completions

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/app/install/route.ts

@@ -81,9 +81,14 @@ say ""
 say "\${GREEN}\${BOLD}Done.\${RESET}"
 say ""
 say "Next steps:"
-say "  1. Restart Claude Code so the MCP tools appear."
+say "  1. Paste your invite link:  \${BOLD}claudemesh <invite-url>\${RESET}"
-say "  2. Join a mesh:      \${BOLD}claudemesh join <invite-url>\${RESET}"
+say "     (joins + launches Claude Code in one step)"
-say "  3. Launch with push: \${BOLD}claudemesh launch\${RESET}"
+say ""
+say "  2. Enable click-to-launch from email:"
+say "     \${BOLD}claudemesh url-handler install\${RESET}"
+say ""
+say "  3. Shell completions (optional):"
+say "     \${DIM}claudemesh completions zsh > ~/.zfunc/_claudemesh\${RESET}"
 say ""
 say "Need an invite? Visit \${BOLD}https://claudemesh.com\${RESET}"
 say ""