fix: improve mobile terminal alternate-screen detection and scrolling

- Revert touch-action: none on .xterm-viewport so xterm.js can fall back
  to its own viewport scrolling when the custom handler doesn't take over.
- Detect alternate screen via reference equality
  (term.buffer.active === term.buffer.alternate) instead of the
  string, which could report normal buffer incorrectly.
- Lower vertical-scroll activation threshold from 4px to 2px and only
  prevent default once a vertical gesture is recognized.
- In normal buffer use term.scrollLines() so xterm.js handles the buffer
  scroll consistently; in alternate screen continue sending SGR 1006
  mouse-wheel sequences to tmux/vim.

Quality gates: typecheck, lint clean, npm test -- --run 87 passed.

.pi-map.index.md

@@ -16,7 +16,7 @@ dir: .
 Trust boundary: index routes, map orients, source decides.
 
 ## role
-A self-hosted web-based project management and Git repository platform with OAuth2 authentication, containerized for Docker deployment.
+Infrastructure and deployment configuration package for a self-hosted project management platform with OAuth2 authentication, providing containerized orchestration, environment templates, and development tooling.
 ## parent
 -
 ## children