Avoid redundant renderer resets during application lifecycle

[deepakganesh78]

Fixes #1967.

Summary

• track whether the renderer currently owns terminal state that needs cleanup
• skip renderer resets during Application initialization and first startup, when nothing has rendered yet
• avoid the duplicate fallback reset after a successful final render
• add lifecycle regression coverage for startup/shutdown reset counts and a full-screen resize redraw failure that must still quit the alternate screen

Validation

• uv run pytest -q tests/test_application.py tests/test_vt100_output.py — 4 passed
• uv run prek run --files src/prompt_toolkit/application/application.py src/prompt_toolkit/renderer.py tests/test_application.py — passed
• uv run pytest -q tests/ — 148 passed, 5 skipped; 4 Windows/non-console failures reproduced unchanged on main (two history-input timing assertions and two NoConsoleScreenBufferError failures)
• targeted mypy reports the same existing trace-callback signature errors at application.py:1119, :1123, and :1126
• GitHub Actions unit tests — 158 passed on every Python 3.10–3.14t job; jobs currently stop at the same three pre-existing mypy trace-callback errors reproduced on unmodified main

[deepakganesh78]

Addressed the resize/alternate-screen lifecycle review in e2c21a7.

Renderer.reset(leave_alternate_screen=False) now keeps cleanup pending while _in_alternate_screen remains active. The new full-screen regression test schedules a resize, forces the resize redraw to fail before Renderer.render(), and verifies final cleanup still quits the alternate screen.

Validation:

• uv run pytest -q tests/test_application.py tests/test_vt100_output.py — 4 passed
• uv run prek run --files src/prompt_toolkit/renderer.py tests/test_application.py — passed
• the regression test fails against the previous behavior with alternate_screen_quit == 0