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>

docs/pi-integration.md

@@ -88,9 +88,11 @@ bypass, and project trust is a decision the person at the terminal makes.
 - **`--api-key`.** Never. It would put a provider secret on the spawn command
   line, visible in `ps`, tmux server state and logs. `PI_*` overrides go through
   socket-scoped `tmux setenv` for exactly this reason.
-- **`--tui-mode`.** Pi's default main-screen TUI is the friendly case for a
-  browser terminal. The fullscreen mode (0.84.0) stays your own runtime choice via
-  `/settings`.
+- **`--tui-mode`.** Which TUI you get stays your choice, in pi's `tuiMode` setting.
+  Fullscreen is the default since pi 1.0.0: the wheel and clicks reach pi, and because
+  Codeman strips pi's mouse enables, a drag selects text in the browser rather than
+  using pi's own selection or scrollbar drag. `tuiMode: regular`, and every pi below
+  1.0.0, is inline with terminal-owned scrollback and emits no mouse enables at all.
 - **`--name`, `--no-session`, `-p`/`--print`, `--mode json`, `--mode rpc`,
   `--tools`/`--exclude-tools`, `-e`/`--extension`, `--skill`,
   `--system-prompt`.** Tracked as follow-ups in the plan doc.