Keep the bottom toolbar visible during nested prompts

[tleonhardt]

Problem

read_input() and read_secret() each build their own PromptSession and passed no bottom_toolbar, while _read_raw_input() is decorated @suspend_toolbar. So the main display stops and the nested prompt has no bar of its own — the toolbar vanishes entirely for as long as the nested prompt is up. For a bar documented as persistent, that is a visible inconsistency.

Driving a real app through a pty, with a toolbar that ticks once per 200ms:

BEFORE   main prompt   : bar=('TICK0024', row 23)
         nested prompt : bar=(None, None)          <- gone

Fix

Pass the toolbar to both temporary sessions when the application has one, gated on main_session.bottom_toolbar is not None so an app without a toolbar does not sprout one at a nested prompt. Also inherit refresh_interval, so a clock or status display keeps ticking rather than freezing at its first render.

Production change is 4 lines.

AFTER    nested prompt t1 : TICK0031     VISIBLE=True
         nested prompt t2 : TICK0038     UPDATING=True

Verified for both read_input() and read_secret().

select() is deliberately excluded

prompt_toolkit's choice() accepts bottom_toolbar and style but not refresh_interval, and ChoiceInput._create_application() constructs its Application without one (verified in 3.0.53). Input-driven redraws would still refresh it, so it would not freeze permanently — but it would go stale while the selection sits idle, and a clock that stops until the next keypress is worse than no clock. Left for a follow-up: either accept a stale-while-idle toolbar there, or upstream a refresh_interval parameter to choice().

Tests

Five added, TDD throughout — each of the four positive tests was watched failing for the right reason before any production code:

Test	Red because
read_input session shows the toolbar	bottom_toolbar was None
read_input session inherits refresh_interval	was 0
read_secret session shows the toolbar	bottom_toolbar was None
read_secret session inherits refresh_interval	was 0

The fifth, test_nested_prompt_has_no_toolbar_when_the_app_has_none, is a guard that passes against correct code by construction. Rather than claim it was red-first, I mutation-checked it: making the assignment unconditional fails it for both methods.

The tests capture the real PromptSession cmd2 constructs and assert on its attributes, rather than asserting on mock call kwargs.

• make check clean (ruff, prettier, typos, ty, mypy --strict)
• make test: 1930 passed, 2 skipped
• make docs-test clean

Docs

docs/features/prompt.md said cmd2 "temporarily hides the toolbar for its input prompts", which this makes false. Corrected, including why select() is excluded. CHANGELOG.md entry added under 4.3.0.

Scope

This is stage 1 of the bottom-toolbar work and is independent of the flicker investigation — it needs none of that machinery and changes nothing about run boundaries. It removes the toolbar's absence during nested prompts, not the repaint: _read_raw_input still genuinely suspends, so entering and leaving a nested prompt still repaints the bar.

Opened primarily to get CI coverage on all supported platforms — particularly Windows and the free-threaded 3.14t jobs — before this merges to consolidated_toolbar.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.67%. Comparing base (68932ec) to head (83a4b68).

Additional details and impacted files

@@                  Coverage Diff                  @@
##           consolidated_toolbar    #1750   +/-   ##
=====================================================
  Coverage                 99.67%   99.67%           
=====================================================
  Files                        25       25           
  Lines                      6464     6464           
=====================================================
  Hits                       6443     6443           
  Misses                       21       21           

Flag	Coverage Δ
unittests	99.67% <ø> (ø)

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