Fixes #7604: Add filter modifier dropdowns for advanced lookup operators

Implements dynamic filter modifier UI that allows users to select lookup operators
(exact, contains, starts with, regex, negation, empty/not empty) directly in filter
forms without manual URL parameter editing.

Supports filters for all scalar types and strings, as well as some
related object filters. Explicitly does not support filters on fields
that use APIWidget. That has been broken out in to follow up work.

**Backend:**
- FilterModifierWidget: Wraps form widgets with lookup modifier dropdown
- FilterModifierMixin: Auto-enhances filterset fields with appropriate lookups
- Extended lookup support: Adds negation (n), regex, iregex, empty_true/false lookups
- Field-type-aware: CharField gets text lookups, IntegerField gets comparison operators, etc.

**Frontend:**
- TypeScript handler syncs modifier dropdown with URL parameters
- Dynamically updates form field names (serial → serial__ic) on modifier change
- Flexible-width modifier dropdowns with semantic CSS classes

netbox/dcim/forms/filtersets.py

@@ -3,6 +3,7 @@ from django.utils.translation import gettext_lazy as _
 
 from dcim.choices import *
 from dcim.constants import *
+from dcim.filtersets import DeviceFilterSet, RackFilterSet, PowerOutletFilterSet
 from dcim.models import *
 from extras.forms import LocalConfigContextFilterForm
 from extras.models import ConfigTemplate
@@ -16,6 +17,8 @@ from tenancy.forms import ContactModelFilterForm, TenancyFilterForm
 from users.models import Owner, User
 from utilities.forms import BOOLEAN_WITH_BLANK_CHOICES, FilterForm, add_blank_choice
 from utilities.forms.fields import ColorField, DynamicModelChoiceField, DynamicModelMultipleChoiceField, TagFilterField
+from utilities.forms.filterset_mappings import FILTERSET_MAPPINGS
+from utilities.forms.mixins import FilterModifierMixin
 from utilities.forms.rendering import FieldSet
 from utilities.forms.widgets import NumberWithOptions
 from virtualization.models import Cluster, ClusterGroup, VirtualMachine
@@ -330,7 +333,7 @@ class RackTypeFilterForm(RackBaseFilterForm):
     tag = TagFilterField(model)
 
 
-class RackFilterForm(TenancyFilterForm, ContactModelFilterForm, RackBaseFilterForm):
+class RackFilterForm(FilterModifierMixin, TenancyFilterForm, ContactModelFilterForm, RackBaseFilterForm):
     model = Rack
     fieldsets = (
         FieldSet('q', 'filter_id', 'tag', 'owner_id'),
@@ -778,6 +781,7 @@ class PlatformFilterForm(NestedGroupModelFilterSetForm):
 
 
 class DeviceFilterForm(
+    FilterModifierMixin,
     LocalConfigContextFilterForm,
     TenancyFilterForm,
     ContactModelFilterForm,
@@ -1420,7 +1424,7 @@ class PowerPortFilterForm(PathEndpointFilterForm, DeviceComponentFilterForm):
     tag = TagFilterField(model)
 
 
-class PowerOutletFilterForm(PathEndpointFilterForm, DeviceComponentFilterForm):
+class PowerOutletFilterForm(FilterModifierMixin, PathEndpointFilterForm, DeviceComponentFilterForm):
     model = PowerOutlet
     fieldsets = (
         FieldSet('q', 'filter_id', 'tag', 'owner_id'),
@@ -1830,3 +1834,9 @@ class InterfaceConnectionFilterForm(FilterForm):
         },
         label=_('Device')
     )
+
+
+# Register FilterSet mappings for FilterModifierMixin lookup verification
+FILTERSET_MAPPINGS[DeviceFilterForm] = DeviceFilterSet
+FILTERSET_MAPPINGS[RackFilterForm] = RackFilterSet
+FILTERSET_MAPPINGS[PowerOutletFilterForm] = PowerOutletFilterSet