Completes Phase 1: Beancount patterns adoption

Implements core improvements from Phase 1 of the Beancount patterns adoption:

- Uses Decimal for fiat amounts to prevent floating point errors
- Adds a meta field to journal entries for a full audit trail
- Adds a flag field to journal entries for transaction status
- Migrates existing account names to a hierarchical format

This commit introduces a database migration to add the `flag` and `meta` columns to the `journal_entries` table. It also includes updates to the models, CRUD operations, and API endpoints to handle the new fields.

views_api.py

@@ -1,3 +1,4 @@
+from decimal import Decimal
 from http import HTTPStatus
 
 from fastapi import APIRouter, Depends, HTTPException
@@ -43,6 +44,7 @@ from .models import (
     ExpenseEntry,
     GeneratePaymentInvoice,
     JournalEntry,
+    JournalEntryFlag,
     ManualPaymentRequest,
     ReceivableEntry,
     RecordPayment,
@@ -231,14 +233,14 @@ async def api_create_expense_entry(
             )
 
         # Convert fiat to satoshis
-        amount_sats = await fiat_amount_as_satoshis(data.amount, data.currency)
+        amount_sats = await fiat_amount_as_satoshis(float(data.amount), data.currency)
 
-        # Store currency metadata
+        # Store currency metadata (store fiat_amount as string to preserve Decimal precision)
         metadata = {
             "fiat_currency": data.currency.upper(),
-            "fiat_amount": round(data.amount, ndigits=3),
-            "fiat_rate": amount_sats / data.amount if data.amount > 0 else 0,
-            "btc_rate": (data.amount / amount_sats * 100_000_000) if amount_sats > 0 else 0,
+            "fiat_amount": str(data.amount.quantize(Decimal("0.001"))),  # Store as string with 3 decimal places
+            "fiat_rate": float(amount_sats) / float(data.amount) if data.amount > 0 else 0,
+            "btc_rate": float(data.amount) / float(amount_sats) * 100_000_000 if amount_sats > 0 else 0,
         }
 
     # Get or create expense account
@@ -267,9 +269,19 @@ async def api_create_expense_entry(
     # Create journal entry
     # DR Expense, CR User Account (Liability or Equity)
     description_suffix = f" ({metadata['fiat_amount']} {metadata['fiat_currency']})" if metadata else ""
+
+    # Add meta information for audit trail
+    entry_meta = {
+        "source": "api",
+        "created_via": "expense_entry",
+        "user_id": wallet.wallet.user,
+        "is_equity": data.is_equity,
+    }
+
     entry_data = CreateJournalEntry(
         description=data.description + description_suffix,
         reference=data.reference,
+        meta=entry_meta,
         lines=[
             CreateEntryLine(
                 account_id=expense_account.id,
@@ -315,14 +327,14 @@ async def api_create_receivable_entry(
             )
 
         # Convert fiat to satoshis
-        amount_sats = await fiat_amount_as_satoshis(data.amount, data.currency)
+        amount_sats = await fiat_amount_as_satoshis(float(data.amount), data.currency)
 
-        # Store currency metadata
+        # Store currency metadata (store fiat_amount as string to preserve Decimal precision)
         metadata = {
             "fiat_currency": data.currency.upper(),
-            "fiat_amount": round(data.amount, ndigits=3),
-            "fiat_rate": amount_sats / data.amount if data.amount > 0 else 0,
-            "btc_rate": (data.amount / amount_sats * 100_000_000) if amount_sats > 0 else 0,
+            "fiat_amount": str(data.amount.quantize(Decimal("0.001"))),  # Store as string with 3 decimal places
+            "fiat_rate": float(amount_sats) / float(data.amount) if data.amount > 0 else 0,
+            "btc_rate": float(data.amount) / float(amount_sats) * 100_000_000 if amount_sats > 0 else 0,
         }
 
     # Get or create revenue account
@@ -343,9 +355,19 @@ async def api_create_receivable_entry(
     # Create journal entry
     # DR Accounts Receivable (User), CR Revenue
     description_suffix = f" ({metadata['fiat_amount']} {metadata['fiat_currency']})" if metadata else ""
+
+    # Add meta information for audit trail
+    entry_meta = {
+        "source": "api",
+        "created_via": "receivable_entry",
+        "debtor_user_id": data.user_id,
+    }
+
     entry_data = CreateJournalEntry(
         description=data.description + description_suffix,
         reference=data.reference,
+        flag=JournalEntryFlag.PENDING,  # Receivables start as pending until paid
+        meta=entry_meta,
         lines=[
             CreateEntryLine(
                 account_id=user_receivable.id,
@@ -447,7 +469,7 @@ async def api_get_my_balance(
         for user_balance in all_balances:
             for currency, amount in user_balance.fiat_balances.items():
                 if currency not in total_fiat_balances:
-                    total_fiat_balances[currency] = 0.0
+                    total_fiat_balances[currency] = Decimal("0")
                 # Add all balances (positive and negative)
                 total_fiat_balances[currency] += amount
 
@@ -579,9 +601,20 @@ async def api_record_payment(
     # Create journal entry to record payment
     # DR Lightning Balance, CR Accounts Receivable (User)
     # This reduces what the user owes
+
+    # Add meta information for audit trail
+    entry_meta = {
+        "source": "lightning_payment",
+        "created_via": "record_payment",
+        "payment_hash": data.payment_hash,
+        "payer_user_id": wallet.wallet.user,
+    }
+
     entry_data = CreateJournalEntry(
         description=f"Lightning payment from user {wallet.wallet.user[:8]}",
         reference=data.payment_hash,
+        flag=JournalEntryFlag.CLEARED,  # Payment is immediately cleared
+        meta=entry_meta,
         lines=[
             CreateEntryLine(
                 account_id=lightning_account.id,