feat: add support for local LLM providers (Ollama & LM Studio)

Implement local LLM inference support for Ollama and LM Studio:

New Clients:
- OllamaClient: Interface to Ollama API (default: localhost:11434)
- LMStudioClient: Interface to LM Studio API (default: localhost:1234)

Factory Updates:
- Added OLLAMA and LMSTUDIO to LLMProvider enum
- Updated create_client() to instantiate local clients
- Updated list_available_providers() with is_local flag

Configuration:
- Added ollama_base_url and lmstudio_base_url settings
- Local providers return configured for API key check

Tests:
- Comprehensive test suite (250+ lines)
- Tests for client initialization and invocation
- Factory integration tests

Documentation:
- Added LLM Providers section to SKILL.md
- Documented setup for Ollama and LM Studio
- Added usage examples and configuration guide

Usage:
  provider: ollama, model: llama3.2
  provider: lmstudio, model: local-model

SKILL.md

@@ -602,7 +602,113 @@ curl http://localhost:8000/api/v1/notebooks -H "X-API-Key: your-key"
 
 ---
 
-**Skill Version:** 1.2.0  
+## LLM Providers
+
+DocuMente supporta molteplici provider LLM, inclusi quelli locali tramite **Ollama** e **LM Studio**.
+
+### Provider Cloud
+
+| Provider | API Key Richiesta | Default Model |
+|----------|------------------|---------------|
+| **OpenAI** | ✅ `OPENAI_API_KEY` | gpt-4o-mini |
+| **Anthropic** | ✅ `ANTHROPIC_API_KEY` | claude-3-sonnet |
+| **Google** | ✅ `GOOGLE_API_KEY` | gemini-pro |
+| **Mistral** | ✅ `MISTRAL_API_KEY` | mistral-medium |
+| **Azure** | ✅ `AZURE_API_KEY` | gpt-4 |
+| **OpenRouter** | ✅ `OPENROUTER_API_KEY` | openai/gpt-4o-mini |
+| **Z.AI** | ✅ `ZAI_API_KEY` | zai-large |
+| **OpenCode Zen** | ✅ `OPENCODE_ZEN_API_KEY` | zen-1 |
+
+### Provider Locali
+
+| Provider | URL Default | Configurazione |
+|----------|-------------|----------------|
+| **Ollama** | http://localhost:11434 | `OLLAMA_BASE_URL` |
+| **LM Studio** | http://localhost:1234 | `LMSTUDIO_BASE_URL` |
+
+#### Setup Ollama
+
+```bash
+# 1. Installa Ollama
+# macOS/Linux
+curl -fsSL https://ollama.com/install.sh | sh
+
+# 2. Scarica un modello
+ollama pull llama3.2
+ollama pull mistral
+ollama pull qwen2.5
+
+# 3. Avvia Ollama (in un terminale separato)
+ollama serve
+
+# 4. Verifica che sia in esecuzione
+curl http://localhost:11434/api/tags
+```
+
+**Uso con DocuMente:**
+```bash
+# Query con Ollama
+curl -X POST http://localhost:8000/api/v1/query \
+  -H "Content-Type: application/json" \
+  -d '{
+    "question": "Spiega l\'intelligenza artificiale",
+    "provider": "ollama",
+    "model": "llama3.2"
+  }'
+```
+
+#### Setup LM Studio
+
+```bash
+# 1. Scarica LM Studio da https://lmstudio.ai/
+
+# 2. Avvia LM Studio e carica un modello
+
+# 3. Attiva il server locale (Settings > Local Server)
+# Default URL: http://localhost:1234
+
+# 4. Verifica che sia in esecuzione
+curl http://localhost:1234/v1/models
+```
+
+**Uso con DocuMente:**
+```bash
+# Query con LM Studio
+curl -X POST http://localhost:8000/api/v1/query \
+  -H "Content-Type: application/json" \
+  -d '{
+    "question": "Cosa sono i notebook?",
+    "provider": "lmstudio",
+    "model": "local-model"
+  }'
+```
+
+#### Configurazione URL Personalizzato
+
+Per usare Ollama/LM Studio su un'altra macchina nella rete:
+
+```env
+# .env
+OLLAMA_BASE_URL=http://192.168.1.100:11434
+LMSTUDIO_BASE_URL=http://192.168.1.50:1234
+```
+
+#### Vantaggi dei Provider Locali
+
+- 🔒 **Privacy**: I dati non lasciano il tuo computer/rete
+- 💰 **Gratuito**: Nessun costo per API call
+- ⚡ **Offline**: Funziona senza connessione internet
+- 🔧 **Controllo**: Scegli tu quali modelli usare
+
+#### Limitazioni
+
+- Richiedono hardware adeguato (RAM, GPU consigliata)
+- I modelli locali sono generalmente meno potenti di GPT-4/Claude
+- Tempo di risposta più lungo su hardware consumer
+
+---
+
+**Skill Version:** 1.3.0  
 **API Version:** v1  
 **Last Updated:** 2026-04-06
 
@@ -667,3 +773,49 @@ curl http://localhost:8000/api/v1/notebooks -H "X-API-Key: your-key"
 - ✅ Created docs/integration.md with full guide
 - ✅ Updated SKILL.md with new capabilities
 - ✅ API examples and best practices
+
+---
+
+## Changelog Sprint 3
+
+### 2026-04-06 - Local LLM Providers (Ollama & LM Studio)
+
+**Implemented:**
+- ✅ `OllamaClient` - Support for Ollama local inference
+- ✅ `LMStudioClient` - Support for LM Studio local inference
+- ✅ Added `ollama` and `lmstudio` to `LLMProvider` enum
+- ✅ Updated `LLMClientFactory` to create local provider clients
+- ✅ Added configuration options `OLLAMA_BASE_URL` and `LMSTUDIO_BASE_URL`
+- ✅ Local providers marked with `is_local: true` in provider list
+
+**Features:**
+- OpenAI-compatible API endpoints (/v1/chat/completions)
+- Configurable base URLs for network deployments
+- Longer timeouts (120s) for local inference
+- No API key required for local providers
+- Support for all Ollama models (llama3.2, mistral, qwen, etc.)
+- Support for any model loaded in LM Studio
+
+**Configuration:**
+```env
+# Optional: Custom URLs
+OLLAMA_BASE_URL=http://localhost:11434
+LMSTUDIO_BASE_URL=http://localhost:1234
+```
+
+**Usage:**
+```bash
+curl -X POST http://localhost:8000/api/v1/query \
+  -H "Content-Type: application/json" \
+  -d '{
+    "question": "Explain AI",
+    "provider": "ollama",
+    "model": "llama3.2"
+  }'
+```
+
+**Tests:**
+- ✅ 250+ lines of tests for local providers
+- ✅ Unit tests for OllamaClient and LMStudioClient
+- ✅ Integration tests for factory creation
+- ✅ Configuration tests