perf: faster Settings, typing and dictation; mypy in CI, engine interface, architecture docs (#968)

* fix(perf): reduce startup and inference overhead

* fix(perf): report effective whisper.cpp fallback settings

* fix(injection): add opt-in X11 paste for long dictations

* perf(vad): lower default silence timeout to 1.2s

* fix(types): resolve mypy errors across application source

* ci: run mypy in the lint job

* ci: include mypy in lint dependency group

* fix(types): narrow evdev timestamp comparison

* refactor(recognition): add SpeechEngine protocol and engine dispatch table

* refactor(settings): move About section and engine tables out of settings_dialog

* docs: add ARCHITECTURE.md and refresh docs index and AGENTS layout

* fix(settings): preserve GTK dialog compatibility after extraction

* style: format touched Python modules

* fix(types): keep local typecheck from syncing dependencies

* test(vad): align main startup expectation with new default

* style: sort engine registry and protocol test imports

* test(settings): follow extracted About builder attribute alias

* test(settings): isolate GTK dialog base in About test

* test(settings): isolate About color scheme build test

* test(settings): restore GTK base after About scheme test

* test(settings): isolate About scheme check from GTK mocks

* test(settings): support extracted dialog mixin methods

* docs: add before/after performance benchmark charts

* fix(injection): type instead of pasting when the clipboard holds non-text data

src/vocalinux/speech_recognition/command_processor.py

@@ -111,7 +111,7 @@ class CommandProcessor:
         }
 
         # Active format modifiers
-        self.active_formats = set()
+        self.active_formats: set[str] = set()
 
         # Compile regex patterns for faster matching
         self._compile_patterns()