Exiting KiCad9 project enhancements

Add a few items to the existing project.
I have KiCad project including Schematic and pcb design. Schematic pdf is attached.

The task is strictly additive. Keep every existing circuit block intact; simply integrate the new parts. Try to keep size almost same (minor increase is acceptable).

Key additions I need

Lithium-ion battery power stage with safe charging and protection (single-cell, USB-C preferred for charge input).
Oled display - appx 2.5 inch
Four colour-coded 3.5 mm audio jacks—Red, Green, Blue and Black—matched to the DS18B20 probe sold here: https://robu.in/product/ds18b20-ip67-thermal-probe-with-3-5mm-audio-jack/
Low-power RTC with battery backup pin broken out (preferable RTC_DS3231).
Clearly labelled test points on all power rails, key GPIOs, and the One-Wire bus for each temperature sensor.
One fixed SHT40 Temperature and Humidity sensor integration
USB C for SDcard data retrieval
Battery

Deliverables
• Updated schematic file in the same CAD tool as the original (prefer KiCad 9).
• Re-routed PCB that fits the original board outline; Gerbers, drill files, and assembly drawings ready for fabrication.
• Short design note explaining battery-charging parameters, GPIO mapping four DS18B20 connectors, plus any new BOM line items.

I will validate the work by importing your files, running ERC/DRC, and cross-checking part references against the design note, so please keep naming consistent. Once everything checks out I will proceed directly to board fabrication, so accuracy is crucial.