feat(flake)!: convert everything to flake-parts-style flake modules

Use `agenix-rekey` flake module
Add `NixOS` module for `agenix-rekey`
- Default `masterIdentities`
- Default `localStorageDir`

secrets/rekeyed/jeeves/09929fb71c71534d52536215c3602e4b-wireguard.privateKey.age

@@ -0,0 +1,8 @@
+age-encryption.org/v1
+-> ssh-ed25519 vMnblg gHW2W1sQQr+QByiUSyEghScmMmu6UI6rAXbQNjpoBhA
+xXPVHDNZDjUZ3GSLOP3EDoao+GNa3a+seSC1YZShauc
+-> <n2-grease @ T/Yh#%V0 % ./^|H
+hGUgkseGEsh7i0DALN0pf1h4IrjsYqkDc9gsk93c/WNvAvsB5aLGV5vascK7sHz+
+G5QTeoRjtcwAklRy0swuNZqOgFw344ssEq14b97XxdwAGTI
+--- Tit/+3FPYExNKp9oLR0Oe4aO5dL50CG2qk55XMLB1m4
+R.¦z‡n<@bIl¾Ÿ)!J)q«O‘³eøÍ@ï&󫿧`¸
¶“ü´“<<3C>ÀCTu<54>Ò…WÄï×v 3À«Èû¨cC%

secrets/rekeyed/jeeves/e824263694cea4631a6bb7e77ec69edf-jeeves.user.password.age

@@ -0,0 +1,7 @@
+age-encryption.org/v1
+-> ssh-ed25519 vMnblg io1ovjOPj67EqZUD9gb8PdJOe04MDtvVk/0gxxNLpz0
+zR3JNHCKEYdudWwekToN8osSr+5yfLSfU5ErINCaUBo
+-> 1To^`-grease hf^(
+viCo
+--- HR02X1joPivzEo6NsI8jr65NnUF9zmuh2RMvoGrsezc
+TBf
p›tp6€ž“€Ó¸ð>Çõ£ƒb!<21>ÄÑ´<C391>PFmsøTÔ뎕<C5BD>c”Ã8 =¢@¬2ÒÙÜkñ\âx\
fÁýb\v <76>†—9n<39>µ7pU ÜAÓÚVE°7‘P>>yl}W…vU2—‡ʯe™j%4z8ˆ?L¸Î":tçz5½ÔŠ

secrets/rekeyed/jeeves/ed5a794780a161567e036b4802c11f91-home.wifi.env.age

@@ -0,0 +1,8 @@
+age-encryption.org/v1
+-> ssh-ed25519 vMnblg vAbvVS3hmYNZsOCA740G8nbXDjMTBtDUd+WiSbY3WRU
+ktnqu2Iw6nPFW/K7yWpP1SEPBguhVgV7QXvs0ykKjQU
+-> O>#~PW-grease V*zH
+PtWg8bdQweiozYPpvJ7KJ1VounffOEM78iNKSnA2+rxmWkAxfyFTd8GoAI5b16DF
+2Q
+--- +MooDUyfXflGR2hPXlS5j7Twn4YZ1Xnhp/7v9lpbOQM
+Ľsď­;(Á¨N2ę9Ld7ô<37>PĂúZZŘ´fĚR­nä0’vso$Ň·Ëúśg¸±j¦Ş­p@NeAŠ€Ď<ý¦ŞÝţ9´Žô»Đ[ŰĽĘ@0¬<30>m_ęp_R