feat(tui): redesign chrome with unified key hints and help overlay

Introduce one key-hint grammar across every view: bold key, dim label,
priority-ordered hints that drop from the end instead of ellipsizing.
The month footer becomes a single split status bar with a friendly
selected date, the '?' mega-line becomes a real keyboard shortcut
panel, and the editor, agenda, search, picker, detail, and delete
frames share the same chips. Notifications carry check/warning marks.
Adds a live PTY smoke test covering view interaction and terminal
state restoration on q and Ctrl-C exits.

meson.build

@@ -46,6 +46,11 @@ nocal_dep = declare_dependency(include_directories: inc, link_with: nocal_lib,
 nocal_executable = executable('nocal', 'src/main.cpp',
   dependencies: nocal_dep, install: true)
 
+util = meson.get_compiler('cpp').find_library('util', required: false)
+pty_smoke = executable('tui-pty-smoke', 'tests/tui_pty_smoke.cpp',
+  dependencies: util)
+test('tui-pty-smoke', pty_smoke, args: [nocal_executable], timeout: 60)
+
 domain_tests = executable('domain-tests', 'tests/domain_tests.cpp',
   dependencies: nocal_dep)
 test('domain', domain_tests)