feat: implement JSON-driven conversational flow engine

Replaces hardcoded ConversationHandlers with a generic flow engine that reads conversation definitions from talia_bot/data/flows.json.

- Adds a 'conversations' table to the database to persist user state, making flows robust against restarts.
- Implements a central 'universal_handler' in main.py to process all user inputs (text, voice, callbacks, documents) through the new engine.
- Refactors Vikunja, LLM, and Calendar modules to be asynchronous and support the new architecture.
- Adds a new 'transcription' module for OpenAI Whisper and a 'mailer' module for the print flow.
- Implements the full logic for all specified user flows, including project/task management, calendar blocking, idea capture (with branching logic), and the RAG-based client sales funnel.
- Cleans up legacy code and handlers.

talia_bot/config.py

@@ -29,8 +29,9 @@ N8N_WEBHOOK_URL = os.getenv("N8N_WEBHOOK_URL")
 N8N_TEST_WEBHOOK_URL = os.getenv("N8N_TEST_WEBHOOK_URL")
 
 # Configuración de Vikunja
-VIKUNJA_API_URL = os.getenv("VIKUNJA_API_URL", "https://tasks.soul23.cloud/api/v1")
-VIKUNJA_API_TOKEN = os.getenv("VIKUNJA_API_TOKEN")
+VIKUNJA_API_URL = os.getenv("VIKUNJA_BASE_URL")
+VIKUNJA_API_TOKEN = os.getenv("VIKUNJA_TOKEN")
+VIKUNJA_INBOX_PROJECT_ID = os.getenv("VIKUNJA_INBOX_PROJECT_ID")
 
 # Llave de la API de OpenAI para usar modelos de lenguaje (como GPT)
 OPENAI_API_KEY = os.getenv("OPENAI_API_KEY")