nav: bind back to backspace as well — a bare Esc isn't reliable in a terminal

Esc-to-go-back needed two presses. It looked like the decomp pane was swallowing
the first one, but the RPC state dump before/after a single Esc settles it:

    nav_depth   3  ->  3      action_back never ran
    cursor.col  19 -> 20      +1 column, i.e. `right`
    modal       null          nothing was up to eat the key

The keypress arrived as a right-arrow. \x1b is both Escape and the lead byte of
every arrow/function-key sequence (ESC [ C is right), so a terminal or tmux that
merges a lone Esc with what follows delivers something else entirely. Nothing in
the nav path touches cursor_x and there is no widget-level escape binding on the
code views, so this was never application logic — I spent two commits looking in
the wrong place before asking for the dump.

Bind back to "escape,backspace". Backspace is unambiguous, so going back never
depends on a byte the terminal can reinterpret; Esc still works wherever it's
delivered intact. tmux users generally want `set -sg escape-time 10` regardless.

docs/TEXTUAL_NOTES.md records the symptom and, more usefully, the triage: check
nav_depth in the state dump first — if the action never ran, it's the input
layer, not the logic.

Verified: backspace in the pseudocode pane takes nav 3 -> 2 and reloads the
previous function. Suite 192/0.

1 files changed, 6 insertions, 1 deletions

diff --git a/idatui/app.py b/idatui/app.py
index 57ec7df..5898489 100644
--- a/idatui/app.py
+++ b/idatui/app.py
@@ -3150,7 +3150,12 @@ class IdaTui(App):
         Binding("ctrl+b", "toggle_functions", "Names", show=False),
         Binding("tab,shift+tab", "toggle_view", "Disasm/Pseudocode", priority=True),
         Binding("ctrl+s", "save", "Save"),
-        Binding("escape", "back", "Back"),
+        # Esc is IDA's muscle memory, but a bare \x1b is ambiguous in terminals:
+        # it's also the lead byte of every arrow/function-key sequence, so a
+        # terminal or tmux that merges it (see tmux escape-time) delivers the
+        # keypress as e.g. "right" and back silently doesn't happen. Backspace
+        # is unambiguous and always works.
+        Binding("escape,backspace", "back", "Back"),
     ]
 
     def __init__(self, open_path: str | None = None, keepalive: bool = True,