fix: resolve migration multiple heads and flake8 F821/F823

- Add merge migration 116_merge_three_heads to join heads
  090_add_push_subscriptions, 100_gantt_colors_modules, and
  115_add_exclude_weekends so 'flask db upgrade' runs cleanly.

- Fix undefined-name and scope issues for CI code-quality:
  - api_v1: import InvalidOperation in amount_paid Decimal block
  - custom_reports, invoice_approvals, reports, scheduled_reports,
    tasks: add current_app to Flask imports
  - integrations: set user_integration before POST branches so
    update_config path can use it
  - invoices: use _ign for unpacking in export_invoice_ubl to avoid
    shadowing gettext _ (F823)
  - data_import, excel_export: add module logger (logging.getLogger)

app/routes/api_v1.py

@@ -1536,7 +1536,7 @@ def update_invoice(invoice_id):
             current_app.logger.warning(f"Invalid tax_rate value in invoice update: {data.get('tax_rate')} - {e}")
     if "amount_paid" in data:
         try:
-            from decimal import Decimal
+            from decimal import Decimal, InvalidOperation
 
             update_kwargs["amount_paid"] = Decimal(str(data["amount_paid"]))
         except (ValueError, TypeError, InvalidOperation) as e:

app/routes/custom_reports.py

@@ -2,7 +2,7 @@
 Routes for custom report builder.
 """
 
-from flask import Blueprint, render_template, request, redirect, url_for, flash, jsonify
+from flask import Blueprint, render_template, request, redirect, url_for, flash, jsonify, current_app
 from flask_babel import gettext as _
 from flask_login import login_required, current_user
 from app import db

app/routes/integrations.py

@@ -317,6 +317,8 @@ def manage_integration(provider):
         # Per-user integration
         integration = Integration.query.filter_by(provider=provider, user_id=current_user.id, is_global=False).first()
 
+    user_integration = None if is_global else integration
+
     # Handle POST (OAuth credential updates - admin only for global integrations)
     if request.method == "POST":
         if is_global and not current_user.is_admin:

app/routes/invoice_approvals.py

@@ -2,7 +2,7 @@
 Routes for invoice approval workflow.
 """
 
-from flask import Blueprint, render_template, request, redirect, url_for, flash, jsonify
+from flask import Blueprint, render_template, request, redirect, url_for, flash, jsonify, current_app
 from flask_babel import gettext as _
 from flask_login import login_required, current_user
 from app.models import Invoice, InvoiceApproval, User

app/routes/invoices.py

@@ -1073,8 +1073,8 @@ def export_invoice_ubl(invoice_id):
 
         svc = PeppolService()
         sender = svc._get_sender_party()
-        recipient_party, _, _ = svc._get_recipient_party(invoice)
-        ubl_xml, _ = build_peppol_ubl_invoice_xml(invoice=invoice, supplier=sender, customer=recipient_party)
+        recipient_party, _ign, _ign = svc._get_recipient_party(invoice)
+        ubl_xml, _ign = build_peppol_ubl_invoice_xml(invoice=invoice, supplier=sender, customer=recipient_party)
         fn = f"invoice_{invoice.invoice_number}.xml"
         return Response(ubl_xml, mimetype="application/xml", headers={"Content-Disposition": f"attachment; filename={fn}"})
     except ValueError as e:

app/routes/reports.py

@@ -1,4 +1,4 @@
-from flask import Blueprint, render_template, request, redirect, url_for, flash, send_file, jsonify
+from flask import Blueprint, render_template, request, redirect, url_for, flash, send_file, jsonify, current_app
 from flask_login import login_required, current_user
 from flask_babel import _
 from app import db, log_event, track_event

app/routes/scheduled_reports.py

@@ -2,7 +2,7 @@
 Routes for scheduled reports management.
 """
 
-from flask import Blueprint, render_template, request, redirect, url_for, flash, jsonify
+from flask import Blueprint, render_template, request, redirect, url_for, flash, jsonify, current_app
 from flask_babel import gettext as _
 from flask_login import login_required, current_user
 from app.models import SavedReportView, ReportEmailSchedule

app/routes/tasks.py

@@ -1,6 +1,6 @@
 import re
 
-from flask import Blueprint, render_template, request, redirect, url_for, flash, jsonify, make_response, Response
+from flask import Blueprint, render_template, request, redirect, url_for, flash, jsonify, make_response, Response, current_app
 from flask_babel import gettext as _
 from flask_login import login_required, current_user
 import app as app_module

app/utils/data_import.py

@@ -4,6 +4,7 @@ Data import utilities for importing time tracking data from various sources
 
 import json
 import csv
+import logging
 import requests
 from datetime import datetime, timedelta
 from io import StringIO
@@ -12,6 +13,8 @@ from app import db
 from app.models import User, Project, TimeEntry, Task, Client, Expense, ExpenseCategory, Contact
 from app.utils.db import safe_commit
 
+logger = logging.getLogger(__name__)
+
 
 class ImportError(Exception):
     """Custom exception for import errors"""

app/utils/excel_export.py

@@ -1,12 +1,15 @@
 """Excel export utilities for reports and data export"""
 
 import io
+import logging
 from datetime import datetime
 from openpyxl import Workbook
 from openpyxl.styles import Font, Alignment, PatternFill, Border, Side
 from openpyxl.utils import get_column_letter
 from app.utils.timezone import convert_app_datetime_to_user
 
+logger = logging.getLogger(__name__)
+
 
 def create_time_entries_excel(entries, filename_prefix="timetracker_export"):
     """Create Excel file from time entries

migrations/versions/116_merge_three_heads.py

@@ -0,0 +1,29 @@
+"""Merge three migration heads into one
+
+Revision ID: 116_merge_three_heads
+Revises: 090_add_push_subscriptions, 100_gantt_colors_modules, 115_add_exclude_weekends
+Create Date: 2026-01-25
+
+Merge revision to resolve multiple heads:
+- 090_add_push_subscriptions
+- 100_gantt_colors_modules
+- 115_add_exclude_weekends
+"""
+from alembic import op
+
+
+# revision identifiers, used by Alembic.
+revision = '116_merge_three_heads'
+down_revision = ('090_add_push_subscriptions', '100_gantt_colors_modules', '115_add_exclude_weekends')
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    """No schema changes - merge only."""
+    pass
+
+
+def downgrade():
+    """No schema changes - merge only."""
+    pass