I just cleaned up and tested the reworked PCB. It passed all the functional tests I can do until I put it back in the feeder. 

It has the following improvements:

• Sensor sensitivity adjustment pots are moved off the main board and are now accessible without opening the feeder.
• The power bank keep-alive pulse, if enabled, turns off while the feeder sensors are on since they draw ~300ma by themselves.
• The PIR now just controls the power to the sensors and the op amp. The 555 controlling the dispensing motor no longer fails to respond to the deposit sensor sometimes.
• ^Due to this it works reliably on 5V, so USB chargers and power banks work fine.
• The motor control 555 reset pin has a resistor/capacitor/diode circuit added so if the deposit sensor gets stuck for any reason it won't cause the dispense motor to run indefinitely. I found it online after searching around. I can't find the actual place I first came accross it but here is a similar solution: https://electronics.stackexchange.com/questions/517168/how-to-bypass-continuous-input-on-trigger-pin-of-555-ic-after-some-time-working
• The motor control 555 is now monostable (it was previously bistable) so that if for some reason the dispense trigger does not fire (no peanuts left, sensor misaligned or unplugged, etc.) it will turn off by itself after 24 secs. This is a pretty long time, and later I might shorten it.
• 1uF from the deposit sensor's op amp input to ground to prevent the blip that sometimes happens when powering up the sensors when sensitivity is turned way up.

Here's a pic of the electronic components as of now. Clockwise from 9 o'clock:

• Main board
• Sensor adjustment potentiometers
• Deposit sensor
• Dispense sensor
• Power 
• PIR

The main board has been reworked a few times. Looks ugly but works ok.

So now I'm ready to put it back in the feeder, do a few more tests, and keep trying.

Also - I'm hating my new project name. "Nerdfeeder" and "Quid Pro Crow" seemed cute, but they are not original and now I feel like the name matters a lot less than what it does. I just need to call it what it is and move on.

I thought maybe "Bird Vending Machine", but someone thought I was going to dispense parakeets or something.

"Vending Machine for Birds" it is.