docs: document recording snackbar indicator

Add the on-screen recording indicator to the README feature list and a snackbar.py API contract block in IMPLEMENTATION.md.

Author: KristianP26

README.md

@@ -34,6 +34,7 @@ That's it.
 - **OpenAI-compatible speech-to-text** - use OpenAI, Groq, or another compatible `/audio/transcriptions` endpoint.
 - **Optional AI cleanup** - fix punctuation, grammar, spelling, and capitalization after transcription.
 - **Fallback providers** - configure backup STT and LLM providers if the primary one fails.
+- **On-screen recording indicator** - a small pulsing pill appears at the bottom-center of the screen while recording and processing.
 - **System tray app** - enable/disable, change hotkey, toggle rewrite, open settings, or exit from the tray.
 - **Microphone selection** - pick your input device and calibrate silence detection.
 - **Post-type key** - optionally press `Enter`, `Tab`, `Space`, or `Backspace` after typing.

docs/IMPLEMENTATION.md

@@ -246,6 +246,23 @@ def get_icon_bytes(state: TrayState) -> bytes: ...
     """Raw PNG bytes for testing without Qt."""
 ```
 
+### snackbar.py
+
+```python
+def snackbar_content_for(state_value: str) -> tuple[str, tuple[int, int, int]] | None: ...
+    """Map a TrayState value to (label, dot_rgb); None for idle/unknown (hidden)."""
+
+def bottom_center_xy(available: QRect, size: QSize, margin: int = 48) -> QPoint: ...
+    """Top-left point centering *size* horizontally in *available*, *margin* above bottom."""
+
+class RecordingSnackbar(QWidget):
+    """Frameless, always-on-top, translucent, click-through status pill at the
+    bottom-center of the primary screen. Pulsing dot + label.
+    Never takes focus or appears in the taskbar."""
+    def show_state(self, label: str, dot_rgb: tuple[int, int, int]) -> None: ...
+    def hide_state(self) -> None: ...
+```
+
 ### settings_dialog.py
 
 ```python