feat: implement HTMX support, DRF filters, and professionalized documentation

- Implement server-side location chaining with HTMX support via `htmx=True` in fields and widgets.
- Update location views to handle HTMX requests and return HTML <option> fragments.
- Add NepaliDateYearFilter and NepaliDateRangeFilter for robust DRF API filtering.
- Expand default `DATE_INPUT_FORMATS` in configuration to support multiple common Nepali date styles.
- Update DRF serializers to automatically respect global `NEPKIT` configuration settings.
- Add `django-filter` as an optional dependency under the `drf` extra in pyproject.toml.
- Correct underlying dependency references from `nepali-datetime` to nepali library.
- Complete overhaul of README.md for premium DX, including new sections for storage behavior, timezone awareness, and API usage.

example/example_project/settings.py

@@ -73,4 +73,12 @@ TIME_ZONE = "Asia/Kathmandu"
 USE_I18N = True
 USE_TZ = True
 
+# django-nepkit settings
+NEPKIT = {
+    "DEFAULT_LANGUAGE": "en",  # Default to Devanagari for fields and widgets
+    "DATE_INPUT_FORMATS": ["%Y-%m-%d", "%d/%m/%Y", "%d-%m-%Y"],
+    "ADMIN_DATEPICKER": True,
+    "TIME_FORMAT": 12,  # 12-hour format with AM/PM
+}
+
 STATIC_URL = "static/"