feat: shared PTY terminal (M12 Tier 3) + readable form controls

- feat(share): host-consented interactive terminal over the relay. The host shares
  a real PTY shell (core/pty_session.py); the guest renders it with pyte and sends
  keystrokes (gui/terminal_widget.py) — vim/top/tab-completion/Ctrl-C work. Runs as
  the host's user (never root). The host reads along live and can type too, e.g. a
  sudo password, which stays local and is never sent to the guest. Off by default.
  Guest also pulls inventory on join (req_full).
- fix(gui): style all form controls (QLineEdit/QPlainTextEdit/spin boxes/combo/
  terminals) dark-on-light-text — Fusion defaulted them to unreadable light-on-light.
- replaces the command/response shell with the full PTY; adds pyte to the gui extra.

Verified end-to-end against the deployed relay (guest keystroke ran on host PTY).

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

CHANGELOG.md

@@ -5,6 +5,17 @@ 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).
 
+## [0.7.0] - 2026-05-21
+### Added
+- **Shared terminal (M12, Tier 3)**: when the host enables it, the session shares a real **PTY**
+  shell — the guest gets an interactive terminal (vim, top, tab-completion, Ctrl-C) running on
+  the host as the host's user. The host **reads along** live and can type too, e.g. a `sudo`
+  password — which stays local and is never sent to the guest. Off by default, host-consented.
+  The guest also pulls the host's inventory on join.
+### Fixed
+- **Input contrast**: all form controls (text fields, spin boxes, combo boxes, terminals) now
+  use the dark theme with readable text (Fusion defaulted them to light-on-light).
+
 ## [0.6.0] - 2026-05-21
 ### Added
 - **Session sharing over the relay (M12)**: a **Share** tab — *Start shared session* (host)