fix: word-by-word payload merging and browser client sample rate ...

- Вставка пробела между последовательными text payload'ами,
  чтобы слова не слипались при потоковой отправке (server.py:152-157)
- Браузерный клиент использует sample_rate из сообщения вместо
  хардкода 44100 (client_browser.html:125,208)
- AGENTS.md: добавлены команды браузерного клиента, gotcha
  про пробел между payload'ами
- docs/05_usage.md: раздел браузерного клиента переписан
  (HTTP-сервер, динамический sample_rate)

chore(browser-client): verbose audio receive and playback logging ...

Log base64 size, sample count, AudioContext state, start time, and
playback lifecycle to diagnose streaming audio silence in browser.

fix(browser-client): robust AudioContext resume and add test tone button ...

- Wait for AudioContext to reach 'running' state after resume().
- Recreate context if it was closed.
- Validate audio context state and non-empty data before playback.
- Add 'Test audio' button to verify browser audio path independently.

fix(browser-client): resume AudioContext on user gesture ...

AudioContext requires a user gesture to leave suspended state.
Resume it on Connect and Speak button clicks and await resume().
Also wrap playback in try/catch and log errors in the UI.

feat(examples): add Python and browser WebSocket clients ...

- examples/client_python.py: streaming TTS client with sounddevice playback
- examples/client_browser.html: Web Audio API based browser client
- docs/05_usage.md: usage instructions for both clients
- pyproject.toml: optional client extras (websockets, sounddevice)
- requirements.txt: commented note about client deps