Add org-agenda-api container builds and fly.io deployment

Consolidates container builds from colonelpanic-org-agenda-api repo:
- Add org-agenda-api input to nixos flake
- Add container-colonelpanic and container-kat package outputs
- Add org-agenda-api cachix as substituter
- Add org-agenda-api devShell for deployment work

New org-agenda-api directory contains:
- container.nix: Container build logic using mkContainer
- configs/: Instance configs (custom-config.el, fly.toml, secrets)
- deploy.sh: Fly.io deployment script
- secrets.nix: agenix secret declarations

Build with: nix build .#container-colonelpanic
Deploy with: cd org-agenda-api && ./deploy.sh colonelpanic

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

org-agenda-api/configs/kat/secrets/git-ssh-key.age

@@ -0,0 +1,42 @@
+age-encryption.org/v1
+-> ssh-rsa gwJx0Q
+ugmhcDkQfVGmgY2b4IY0DT9ORMInX+qa8HSaes5RmNItUeRP3ufIeXvSVKC+R0zV
+YCqOf2uyLyjUIOupRKw/1kTh5Jr+74tX2ug4C8dD2A132yDpyziuA1AoKP3P5Uhp
+M1pBA9/QtIwzZByA7gYd5aU7SIqXHR/+DM/dnt/uuKXqKfvDPJrCZWcXIbf2k7xP
+Tyd6NBWfbVmUFZi23qLzN9ugl51Wq7VOvvIpzh+trKFmeTuMyvMCjhRGr/m50sGs
+y3HRMuoXnkTAKXRZ4aQpHGhTwnVgS3SJWHzhH6OVn2ReSObOKZHieYl55kqcJc99
+0ONaWAy54klsa9uHTO4C6w
+-> ssh-ed25519 YFIoHA a6Mdqeh2kYAKiD5etrZiFIlXZaeFcaMooabCWFyG1D0
+zkHFO8d7/I7qnLchwv3ONNqaxqwenX6o/0ky8Z2A+W0
+-> ssh-ed25519 KQfiow vuC5xZ6WYVrpqv44zyNAqFqKlA221SPdpBSm4mlpSU0
+9yXSgczQxZviQf4ZpsAwKa+JOxWH/MQsU5dq4+94Xyc
+-> ssh-ed25519 kScIxg Jy61wrM+pU7QzEIHO9WRJ3KDNKfFk1ekylqRSgzKwVc
+h3ZHKf+cFeGVjgXwof9KlLyDtx43vaSafzgrOiQXe5I
+-> ssh-ed25519 HzX1zw 1en9ihLijagyKd0c7QMJYtH96oIX2phAhJQqM4ysBi4
+JOBDfrom9qo1ZUn99jcxva3DP58yWOIFzwQebJx/158
+-> ssh-ed25519 KQfiow WCcqJwJoqy0dnOb/aUe8oW4BGmkZ4PwEijFJEI1o1ho
+WLjp7UxiY5Kfwq+z5JQzapxUhncZTfsjMUi7FdMtpTU
+-> ssh-ed25519 1o2X0w aOnNDcvUxNjHT9nKDWvlOBPg2nFUHiweT8oz6vvdF2M
+L/PXsInIR+iN/2GStkkL7dnJR1aekne8vfgHi3wADck
+-> ssh-ed25519 KQ5iUA PNAoXHVxtqbzzBfyfdPm4zVBi/ck3Pu5AQpGVqXpQyE
+C98+eL5rcKXgI41iikybPrKC3Zr+uFMTyQOWczOulhs
+-> ssh-ed25519 AKGkDw lDwdoiwK/TKbxDORSggj7wFqoQMguUrzWuqpMZz2Y0U
+rezIK003vf5Jqr7yMED2A6AzIuywDK4TZDYOAGxr5WI
+-> ssh-ed25519 0eS5+A btXiZqnbH6Q0uYNAeu95W6X1h2j8a8MDJNSRYPGYyg0
+0/wsL9Va6+db9BEJ/TJEg6gLo7HbdzLpPKdgUiTqoMc
+-> ssh-ed25519 9/4Prw RMEfjY5nsrEAKFn4IyLD3OyzNVmxgVG3tfNJ4CTbryA
+7PaRcNos01e83BrxgjR9C1FizAlqY+pq+er5lVwVn0w
+-> ssh-ed25519 gAk3+Q ktstz8AM5OafJekAf3SDdIi3VJXudT7q3dWx2hUSWWE
+Yyu/Vudc6aXQXyCQ6rRvFFer5d8IeHegNnpb19UODfs
+-> ssh-ed25519 X6eGtQ nGjC6TfQPXxDnbDVlR8OC6IID2a8uHMkBsft9AvoDzE
+zGue+yzKNJTTOEsRMf1KGTxqjRAEfqII40t5MTMqoYU
+-> ssh-ed25519 0ma8Cw dvgCcSrhVazWrmhkOd60NKLB5nZliQNpdiDYQCDYaAE
+6GtVprnzy25LtPYtqynoZ+Jy4SI1Y8h0jToAueURptg
+-> ssh-ed25519 Tp0Z1Q c8MDIlbXAWC9IWMJMg7HvOBdd4ujm67TyyhjBt2lcio
+2sRBX77p6C+4ZZsiZRLSkyIffVoJL4LFfMFiDMKhvxg
+-> ssh-ed25519 ePNWZQ Uz1bLbcA/U0aU0BCY/VR8HQU5G1CKg+duSkyXVHbk2k
+1vyIWbDlw9YotcHhZ0rIVTaBiiUSsqFs4QVsMfTlreY
+-> ssh-ed25519 hILzzA RWNiC+y7F1XzHMuiM7EQymDH2kyxUhKhRw7og3/frwI
+MjcexeBdoWG0Sskj86zD5M9aRCT8cJcMkbiF0osDmV0
+--- yE8GNNA+dIpXZeFOX9zJYI39UPeTN3hYaaLsdOWk6PI
+{P<><50><1B>_<EFBFBD>'<27><>_<>#<23><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><1F><03>L<EFBFBD><4C><14>W<>d󂫥NWQ<57>}<7D>	<0E><><EFBFBD><EFBFBD>૆<EFBFBD><E0AB86>(<0C>@<0F><>M<EFBFBD><4D><EFBFBD><0B>k<><6B>H<EFBFBD>&<26>s<><73>z<05><>k<6B>i<EFBFBD><69>Z.