fix(share): terminal scrollback for large output

Render with pyte.HistoryScreen and show scrollback + screen, so large output
(ls -la, cat, etc.) can be scrolled up to read. Auto-scroll to the bottom only
when already at the bottom; preserve position when the user has scrolled up.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -5,6 +5,11 @@ All notable changes to RigDoctor are recorded here. Format follows
 (`MAJOR.MINOR.PATCH`, pre-1.0). `__version__` and `pyproject.toml` must match the git
 release tag (so the auto-updater, D18, can compare versions).
 
+## [0.7.3] - 2026-05-21
+### Fixed
+- Shared terminal now has **scrollback** — large output (e.g. `ls -la`) can be scrolled up to
+  read; it keeps a history buffer and only auto-scrolls to the bottom when you're already there.
+
 ## [0.7.2] - 2026-05-21
 ### Changed
 - Removed the GUI **Inventory** tab — use the CLI `rigdoctor inventory` instead. (Inventory is