Typically, if the NSS failed, the motor would not turn over. Is that the situation here?
If you are able to start the car in gear with the clutch pedal depressed? There's also a clutch safety switch.
There should be a programming button near the hood release lever. You should be able to use this to disable the alarm system and get your forester started.
Forgive me for this sloppy answer but I'm just taking a break from my work. Here is the starting system from the 2010 manual but I think it is the same. Hopefully it helps narrow down which part of the system is failing.
The BCM handles the immobilizer but if this is having issue's you should have current or history DTC's in both the bcm and ecm. Usually ...
Some vehicles have a coolant temp sensor that adjusts how rich the fuel mixture is depending on temperature.
I have heard that disconnecting the sensor simulates a cold start. You might as well give this a shot. If it starts with the sensor unplugged, then you probably have a bad sensor.
The battery seems like it has plenty of power, so it it likely being charged properly. The click you are hearing is probably the starter solenoid (electronic switch) closing, but either it isn't sending power to the starter motor, or it is but the starter isn't working.
So it is most likely a bad starter motor, a bad starter solenoid or there could be ...