🚀 Feat: support multiple models + add configuration UI

[nicofretti]

Description

• Added LLMConfigManager for centralized model configuration with database persistence
• Created Settings UI page with model CRUD operations and connection testing
• Migrated .env LLM settings to database on first startup
• Updated TextGenerator and StructuredGenerator blocks to use configured models
• Fix pipeline generation loading

Related Issue

Closes #31

Checklist

• Code follows project style guidelines
• Comments explain "why" not "what"
• Documentation updated (if needed)
• No debug code or console statements
• make format passes
• make pre-merge passes
• PR update from develop branch
• Copilot review run and addressed

[Copilot]

Pull Request Overview

This PR implements multi-model support with a configuration UI for managing LLM and embedding models. It introduces a centralized model configuration system that stores model settings in the database and provides a Settings page for managing configurations.

Key Changes:

• Added LLMConfigManager for centralized model configuration with database persistence
• Created Settings UI page with model CRUD operations and connection testing
• Migrated .env LLM settings to database on first startup
• Updated TextGenerator and StructuredGenerator blocks to use configured models

Reviewed Changes

Copilot reviewed 25 out of 30 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
lib/llm_config.py	New configuration manager for LLM and embedding models with provider-specific logic
lib/storage.py	Added database tables for model configs, error field to jobs, and .env migration
lib/blocks/builtin/text_generator.py	Refactored to use LLMConfigManager instead of direct settings access
lib/blocks/builtin/structured_generator.py	Refactored to use LLMConfigManager instead of direct settings access
lib/job_processor.py	Added error message capture for failed job executions
models.py	Added LLMProvider enum and model config classes with validation
app.py	Added 12 new API endpoints for model management and injected model options into block schemas
tests/test_llm_config.py	Comprehensive test suite covering CRUD, fallback logic, and provider detection
frontend/src/pages/Settings.tsx	New settings page with model management, testing, and CRUD operations
frontend/src/components/settings/*	Modal forms for LLM and embedding model configuration
frontend/src/services/llmConfigApi.ts	API client for model configuration endpoints
frontend/src/contexts/JobContext.tsx	Improved polling logic with proper cleanup and edge case handling
frontend/src/pages/Generator.tsx	Fixed generating state management and removed unused navigation
frontend/src/App.tsx	Added Settings route and React Router future flags
frontend/src/types/index.ts	Added type definitions for model configs and connection test results
llm/*.md	Added comprehensive technical documentation for project architecture
docs/template*.md	Added detailed template documentation with usage examples
*_code_guide.md	Added coding standards and best practices guides
.github/instructions/*.instructions.md	Added code review guidelines
Makefile	Modified run command (contains bug)
.gitignore	Removed llm/* exclusion to allow documentation commits

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[Copilot]

Pull Request Overview

Copilot reviewed 28 out of 33 changed files in this pull request and generated 6 comments.

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