fix(tui): repaint transcript on tmux detach/reattach

[Fullstop000]

Problem

In a tmux/screen session, detaching and reattaching left the TUI blank — the conversation history appeared lost.

Root cause

Since #89 the TUI runs in alternate-screen Viewport::Fullscreen, so the whole transcript lives in app.transcript (in memory), not in the terminal's scrollback. On reattach:

1. tmux re-sends the window size via TIOCSWINSZ → SIGWINCH even when the size is unchanged.
2. crossterm surfaces this as Event::Resize (emitted on every SIGWINCH, no size dedup).
3. The console loop dropped Event::Resize into _ => {}.
4. ratatui's autoresize only repaints when the size actually changed, so the diff renderer wrote nothing → the pane tmux reset on reattach stayed blank.

The data was never lost — it just never got redrawn.

Fix

Handle Event::Resize by forcing a full redraw via terminal.clear() (resets the back buffer so the next frame repaints the entire transcript). 4 lines in runner.rs.

Verification

A/B test with the real binary under tmux — render, wipe the alt-screen out-of-band (simulating tmux's reattach reset), deliver a same-size SIGWINCH, re-capture. Signal confirmed delivered to both binaries:

Binary	rendered → wiped → after reattach signal
Unfixed (master)	✅ → blank → stays blank ❌
Fixed (this PR)	✅ → blank → restored ✅

cargo build, cargo clippy --workspace --all-targets -- -D warnings, and cargo test --workspace (527 passed) all clean.

Scope note

This fixes the reattach blank only. It does not restore native mouse-copy or terminal-native scrollback — both are separate costs of the alt-screen model (#89 / mouse capture in #125). Those would need an inline-rendering change, tracked separately.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 76.47%. Comparing base (da202d0) to head (52f217e).

Files with missing lines	Patch %	Lines
ignis/src/console/runner.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #128      +/-   ##
==========================================
- Coverage   76.47%   76.47%   -0.01%     
==========================================
  Files          66       66              
  Lines       17440    17441       +1     
==========================================
  Hits        13338    13338              
- Misses       4102     4103       +1     

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[Fullstop000]

Superseded by #131 (inline rendering). With the conversation in the terminal's native scrollback, tmux detach/reattach persistence is inherent — the clear()-on-resize band-aid here is no longer needed. Closing in favor of #131.