refactor: rename uses_3v3 to uses_vapwr

The flag enables a second power supply (VAPWR), not necessarily 3.3V (gf180's core is already 3v3), so "uses_3v3" no longer accurately describes its purpose.
Rename it across project_info, precheck, project and shuttle, and update the validation message accordingly.

The legacy "uses_3v3" key is still accepted when reading info.yaml, so existing project configs keep working.

precheck/pin_check.py

@@ -112,14 +112,14 @@ def parse_dbu_to_nm(value: str, dbu_per_micron: int):
 
 
 def pin_check(
-    gds: str, lef: str, template_def: str, toplevel: str, uses_3v3: bool, tech: str
+    gds: str, lef: str, template_def: str, toplevel: str, uses_vapwr: bool, tech: str
 ):
     logging.info("Running pin check...")
     logging.info(f"* gds: {gds}")
     logging.info(f"* lef: {lef}")
     logging.info(f"* template_def: {template_def}")
     logging.info(f"* toplevel: {toplevel}")
-    logging.info(f"* uses_3v3: {uses_3v3}")
+    logging.info(f"* uses_vapwr: {uses_vapwr}")
 
     # parse pins from template def
     # def syntax: https://coriolis.lip6.fr/doc/lefdef/lefdefref/DEFSyntax.html
@@ -201,7 +201,7 @@ def pin_check(
     rect_re = re.compile(r"RECT (\S+) (\S+) (\S+) (\S+) ;")
 
     power_pins = ["VGND", "VDPWR"]
-    if uses_3v3:
+    if uses_vapwr:
         power_pins.append("VAPWR")
     compat_pins = {"VPWR": "VDPWR"}