docs: sync shell/keybinding docs with the rest of the branch

Update the interactive-shell README and keybindings reference for changes
made after the initial docs commit: no scheduled GC (manual only),
NO_TMUX escape hatch, default-terminal tmux-256color + truecolor, the
JetBrainsMono Nerd Font (new Fonts section + iTerm2 caveat), the
UseKeychain IgnoreUnknown guard, and the vim-tmux-navigator (Ctrl-hjkl) +
resurrect save/restore tmux bindings.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyrathorpe/home/KEYBINDINGS.md

@@ -133,16 +133,21 @@ Prefix is **`Ctrl`+`b`** (default). Copy mode uses **vi** keys.
 | --- | --- |
 | `Ctrl`+`b` then `v` | Split into left/right panes |
 | `Ctrl`+`b` then `s` | Split into top/bottom panes |
+| `Ctrl`+`h`/`j`/`k`/`l` | Move between panes — and into/out of vim splits — seamlessly (vim-tmux-navigator, no prefix) |
 | `Alt`+`←`/`→`/`↑`/`↓` | Switch pane by direction (no prefix needed) |
 | `Ctrl`+`b` then `[` | Enter copy mode (then vi motions; `Space`/`Enter` to select/copy) |
 | `Ctrl`+`b` then `z` | Zoom / unzoom the focused pane |
 | `Ctrl`+`b` then `c` | New window |
 | `Ctrl`+`b` then `n` / `p` | Next / previous window |
 | `Ctrl`+`b` then `d` | Detach |
+| `Ctrl`+`b` then `Ctrl`+`s` / `Ctrl`+`r` | Save / restore the session (resurrect; continuum also auto-saves and restores on start) |
 | Mouse | Enabled — click to focus, drag borders, scroll, select |
 
 > The stock split keys `%` and `"` are unbound; use `v` / `s` above. `Ctrl`+`b`
 > then `s` is therefore a split, not the session tree.
+>
+> Sessions persist across reboots (resurrect + continuum). Terminals auto-start
+> tmux; `NO_TMUX=1 <terminal>` opens a bare shell instead.
 
 ---