turny: fix SPI/GPIO config for newer kernels

- Add complete config.txt settings with u-boot boot lines + spi=on
- Override sdImage.populateFirmwareCommands to use configtxt module output
- Mount firmware partition and add activation script to sync config.txt
- Load spi_bcm2835 and bcm2835_gpiomem kernel modules
- Add udev rule for gpiomem subsystem (not just gpio)
- Relax ProtectKernelTunables so service can access GPIO
- Update turny flake input to rppal-based CS pin fix

secrets/gotosocial.age

@@ -1,10 +1,9 @@
 age-encryption.org/v1
--> ssh-ed25519 osOCZA VAbqavKlZzuLT1XwcdWuRX39bNPbuVvsGPXNv5lwd2g
-4mMBgBCfnnbY6lo7WAnppqEk8tA1A5MGvXjjZ84cr5k
--> ssh-ed25519 DFiohQ hzICSaoG/iPl1VEm7gF49mXCzhVZypQN00/9dqbAfgI
-VM5O8wLvzFyFkttqP4YWQ0bR5iKkAvpYFPsep2nYt7E
--> ssh-ed25519 PT7ffg +FbUxPiTEBDl4QdwYUSuqD0+xzHWe4X9l1cqRePwZzQ
-tfKlhCQ0mK67E8UcXki9y4SmgTLsrZwD6kKBQz1NiSI
---- tnLRJm+/eP6KzNV7vD1d2KtDe6SRyo2MoIsow4CDyrU
-±lù•þe–bö±¹D.Û␍c‰Y.êÓdÎNáWä݃ξ^®Å´ï©PщSFd.Ú=ýŸ3øA@I9/Ž¼˜læó›Í�~;FÒR5[|
-s‹
+-> ssh-ed25519 osOCZA OKLTpDP78xbkZ2uxMaJtOIVCd3/jbAV98E9yFGg0SHk
+1RwoL09ZccJhYWJxy/JgMxJSHc74RsKD22L3c13BARo
+-> ssh-ed25519 DFiohQ us/uB+O7gBPPJ3ewzn1Vpkc59obSQcwSORFIhPsw0Wo
+dW/6eaPCKI0Z59PPtoNiOWoaNPNFqy1WPhI2y+AXXok
+-> ssh-ed25519 PT7ffg Shf65NGS/njVgmsKYzH0G+R3Lbul24ov1YX0D8yCVlE
++V8lgVMK4tIIvjWXDRSK15Ko4lf9dBbd3BVnLm4zl7Y
+--- YLhHK7p69aBksuFUcoRIfh9xej8HsQcDgrCUEyw4x64
+#\)V×¹ç{÷ËƽOøHK1lNæ(ˆß*ÒQ	^\aÉ�
z(Ì?A»ý©·(#$Õè3Q” ·„¸£�K	ã…p"I‘s)¼‡‹;½É1%