Update README.md with Gemini Integration

[Olbrasoft]

Parent Issue

#599

Description

Update README.md to reflect Gemini CLI integration in architecture diagram and features.

Changes Required

File: README.md

1. Update Architecture Diagram

Add Gemini CLI to system diagram (around line 19-43):

┌─────────────────────────────────────────────────────────────────────────────┐
│                            VirtualAssistant                                  │
├─────────────────────────────────────────────────────────────────────────────┤
│  Notification Sources:                                                       │
│  - Claude Code (MCP mcp-notify) ────────► Agent: claude-code (male voice)  │
│  - OpenCode (plugin notify.js) ─────────► Agent: opencode (male voice)     │
│  - Gemini CLI (MCP mcp-notify-gemini) ──► Agent: gemini (female voice)     │
│                                                                              │
│  Voice Selection:                                                            │
│  - TtsProfiles configuration maps agent to voice                            │
│  - Azure TTS primary (Antonín/Vlasta)                                       │
│  - EdgeTTS, VoiceRss, Google, Piper fallback chain                         │
└─────────────────────────────────────────────────────────────────────────────┘

2. Update Features Section

Add voice differentiation feature:

## Funkce

- **Voice-to-OpenCode** – hlasové příkazy směrované do AI coding agenta
- **Multi-Agent Support** – Claude Code, OpenCode, Gemini CLI s různými hlasy
- **Agent-Specific Voices** – Mužský hlas (Antonín) pro Claude/OpenCode, ženský hlas (Vlasta) pro Gemini
...

3. Add Example Section

## Příklad Použití

### Notifikace z různých agentů

\```bash
# Claude Code - mužský hlas
curl -X POST http://localhost:5055/api/notifications \\
  -H "Content-Type: application/json" \\
  -d '{"text": "Build dokončen", "source": "claude-code"}'

# Gemini CLI - ženský hlas
curl -X POST http://localhost:5055/api/notifications \\
  -H "Content-Type: application/json" \\
  -d '{"text": "Analýza hotova", "source": "gemini"}'
\```

Acceptance Criteria

• Architecture diagram updated
• Features section includes voice differentiation
• Example commands added
• Agent support clearly documented
• Formatting matches existing style