fix(pi): leave page keys out, and pin the strip that makes the wheel work

transcriptPageKeys applied to every pi, and a pi in `tuiMode: regular` binds
PageUp/PageDown to its editor. It emits no mouse enable, so the flag stays
false, and on a fresh pane the buffer is hollow: the wheel sent PageUp, the
caret of a multi-line draft moved, and the next keystroke landed on the wrong
line. Measured on real pi 1.1.0, 1.4.0 and 1.5.0. Regular mode is not exotic,
it only takes one line in pi's settings. Telling the two modes apart would
need a new capability, since the paging gate takes no id, so pi has no
fallback: a fullscreen pi with "Wheel scrolls local history" on stays where
master left it.

altScreen, the half of the fix that does the work, was pinned by nothing:
reverting it left 1328 tests green. The strip decision table reads its
expected value from the same registry entry. pi now has its own block using
the bytes it really emits, which also pins that focus reporting survives.

The fullscreen default dates from pi 1.0.0, not 1.4.0, so the comments say
that, and the sites still calling pi narrow-strip or main-screen by default
are corrected. Where a comment listed CLIs it now names the capability.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/types/session.ts

@@ -956,8 +956,8 @@ export interface SessionState {
   /**
    * True while the CLI in the pane has a mouse-tracking DECSET on, as observed
    * by the server on its way out of the stream (those sequences are stripped for
-   * the strip-full and strip-mux-and-mouse modes, claude/codex/gemini and opencode
-   * under tmux, so the browser can never see them itself). The browser
+   * the strip-full and strip-mux-and-mouse modes under tmux, so the browser can
+   * never see them itself). The browser
    * hand-encodes a click report ONLY when this is true; without it, every click
    * sent mouse reports to a CLI that never asked for them.
    */