feat: Transform to web architecture with FastAPI backend

This major update transforms leggen from CLI-only to a web-ready
architecture while maintaining full CLI compatibility.

New Features:
- FastAPI backend service (leggend) with comprehensive REST API
- Background job scheduler with configurable cron (replaces Ofelia)
- All CLI commands refactored to use API endpoints
- Docker configuration updated for new services
- API client with health checks and error handling

API Endpoints:
- /api/v1/banks/* - Bank connections and institutions
- /api/v1/accounts/* - Account management and balances
- /api/v1/transactions/* - Transaction retrieval with filtering
- /api/v1/sync/* - Manual sync and scheduler configuration
- /api/v1/notifications/* - Notification settings management

CLI Enhancements:
- New --api-url option and LEGGEND_API_URL environment variable
- Enhanced sync command with --wait and --force options
- Improved transactions command with --full and --limit options
- Automatic fallback and health checking

Breaking Changes:
- compose.yml structure updated (leggend service added)
- Ofelia scheduler removed (internal scheduler used instead)

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

pyproject.toml

@@ -3,7 +3,7 @@ name = "leggen"
 version = "0.6.11"
 description = "An Open Banking CLI"
 authors = [{ name = "Elisiário Couto", email = "elisiario@couto.io" }]
-requires-python = "~=3.12"
+requires-python = "=3.12.0"
 readme = "README.md"
 license = "MIT"
 keywords = [
@@ -31,6 +31,10 @@ dependencies = [
     "tabulate>=0.9.0,<0.10",
     "pymongo>=4.6.1,<5",
     "discord-webhook>=1.3.1,<2",
+    "fastapi>=0.104.0,<1",
+    "uvicorn[standard]>=0.24.0,<1",
+    "apscheduler>=3.10.0,<4",
+    "tomli-w>=1.0.0,<2",
 ]
 
 [project.urls]
@@ -38,6 +42,7 @@ Repository = "https://github.com/elisiariocouto/leggen"
 
 [project.scripts]
 leggen = "leggen.main:cli"
+leggend = "leggend.main:main"
 
 [dependency-groups]
 dev = [