Per a request by PM, I've uploaded a schematic which can easily be expanded to 4 zones.
It does mean that the control of the lights are at a central panel and that home runs are run to each lamp zone. A "home run" means a single cable.
There may be a zone which does not have a corresponding sprinkler and that's OK too.
If it were me, I'd like a switch at the entrance of the home which would turn on all the lights. That could be done using X-10 technology and say a 4PDT relay.
While multiple 4PDT relays could be used, they could easily be replaced with a solid state equlivelent. So, in esscence multiple 4PDT relays or solid state replacement could expand the number of zones by a multiple of 4.
This does not address cost. Bosch 12 V 30 Amp relays are inexpensive. It's possible that high current DC rated contact relay with a 24 VAC coil is expensive.
So, again a choice could be made to use the inexpensive relays and detect the presence of the 24 VAC optoelectrically and activate a 12 VDC coil.
This could easily be accomplished using the DIN rail and the enclosure system with the 1/8" aluminum plate in the bottom. The construction technique is expensive, but it's easy to troubleshoot.
The major concern is picking a relay with a 24 VAC coil which can switch DC at or above the needed current. Power = VI. You know the wattage of the lamps, the number of the lamps and V=12, so you can figure the current I or contact rating needed for each zone. Surplus relays are a good place to start.
The switches could be a mineature toggle switch or the industrial type switches with switchblocks (very expensive).
Two AC rated breakers would complement the system. One for the light power and one for the sprinker power.
Not knowing the number of zones and the current drawn for each zone, makes it tough to design something.
Later, one could change the "all lights on" switch to say "Lights: (on, auto, remote). Remote would be through an X-10 module, auto: controlled by sprinker and ON. I haven't thought this function through yet. "auto" is "controlled by sprinkler"
I'll be happy to answer any questions.