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/colonelpanic/secrets/auth-password.age

@@ -0,0 +1,40 @@
+age-encryption.org/v1
+-> ssh-rsa gwJx0Q
+DPbChrJRIw/0GNKJFW0yVpHj/nS0De/I3t9z+tlqL9BFUpIKBNBZeLBW92xPdTgq
+wAlDKj5Zl1qrxTga4DcHkzA7QJVhTg3GNnEeJqBwaToPb4yEyiToW8B05xjkSrMM
+fPQ+ZkSbdTfupPrfjmnaHED/4RJXJFt2LvdI1dW4XSPdk4rp7oVbs3dnNqWObAhD
+ATiQETPLJ33gAdyrM7A5xo7mwRBV+Kvjr+HrXX9dR3LhcMdecAVBbqI0508VjxvQ
+XP2q30jfavX6x1cNuHNP9UbKRWFZrRvbxi2soz7V7wM5hSiJIuVuYS2Y0hGdIGJy
+SdSozcsa2wJ/aobH4fMImg
+-> ssh-ed25519 YFIoHA 0bHvbcnQZjfBkScK0vXJXjTVzAjPRiUz2wn3l1vQplI
+2wmc1m1XT0f1nHRlgfAGvBJ1xFM84Y0/pVvTSPyxFOU
+-> ssh-ed25519 KQfiow QFs5J3qngIVkFSae2SN1WWtHKzaNvWeaqw/I6Cukbys
+k1YNLwNCKjZNUkwM7CwIEK8FcICPElPr94JEXM4bYrI
+-> ssh-ed25519 kScIxg ucsEcywwdpkDxL327bgvegJXx7/tQf5DZkxl/82bxDY
+BjaZ78vGeZz54/JK+on8TEaQpK7LHmuZ6OtAyszMjV4
+-> ssh-ed25519 HzX1zw VQtRquhDhEFTRBa0S0gVEJW90AeTb5hPe8bXJAyxyXw
+rcUxBPvkIJUk3fvY6vGZgY+mCSzQLDFmKJ5tYafDvAc
+-> ssh-ed25519 1o2X0w +6SwM5hLyc8wvbxBDJbfivjV+wN7whIgFRdX5z2LiCQ
+a+UxJ2YKAWV+XJtOluMvq/8p0nfw27lF2JOzvCYHkmg
+-> ssh-ed25519 KQ5iUA 8BSg4c4T4y0w3msKAmLZJY+J+oHw25mPPlKdFkj5Mlg
+PsAz9C4XthB/hfn/F4IJ9Ifq280B9IXix0C1mk9RyI8
+-> ssh-ed25519 AKGkDw KcGz1q5Fe5RdnYKQtHZpuZtcUtdYysxxzGm10rSFvQ8
+/j2QuqhT1xQDjz/N6KGsBmEGIaL+Cm10YNHeZ6Sw+VU
+-> ssh-ed25519 0eS5+A QLIh5xJ3+A9eeGMkvzbk01HNi41CaTjRGN75y00SSl0
+/Axjo9OeRpgTYxfugpiAeQTiTEtbUgUXWc1Rg7aggI0
+-> ssh-ed25519 9/4Prw 7jpwaON0KKlubIDN3/xllVX7pZhJRoaMVnX5Sc7+wkw
+ObueU1r7o5F9D0e/DxZkU40AsN9lXK5eOcF0N2M1H0g
+-> ssh-ed25519 gAk3+Q cklYccOHJ2HFT7m3Oje8McxLif8kOma0h36ERo2uEC8
+2pPIQfO+V45jdFEZCFRUUFGY1aZWindpoPbCLE1Mies
+-> ssh-ed25519 X6eGtQ IOpU7iT9w8Dmehx/LEA1Cpr8BnAIFwl2sOj8ZZiY00I
+dfx6A+tL7Xc4PXRdt6zxh2rtrB3Wb5HhAhpHT+n9cx0
+-> ssh-ed25519 0ma8Cw C0hjuEmVLn+djtVvJURuVi8b47JVEcux84P6QoX/fGs
+Vnf3b3kU5zFyW9Km+idxgIlx+CFusnKBdN5sOsB/hVk
+-> ssh-ed25519 Tp0Z1Q x4jysmX0AOaOWc0hiTzBA2Lwjwza5G/cqfcP22NuiC8
+pC3MxtgfZHQ1sk/JLtsBKUXPkkC53vH49OVwrWypq1A
+-> ssh-ed25519 ePNWZQ QPNC4Hw4cLAgZgso+Vgqz60sBd1wUgOVUqxl7yYMEkQ
+99w0DohDiy6fXwbKHZYcFZNSvCUroxBxerHVPKY16lg
+-> ssh-ed25519 hILzzA 8tShLcIvpPifSyY0OjKH2fj2F0rgHAol0LRSAAE+7Vw
+9K3iKvI+KKhjY75rWt3n0v9Bz4yqP548PTgWi35c9m4
+--- foeVPG32rt4SIuJ0BtwWh+mTUVoQipAapftZUIA/7gw
+=<3D><><EFBFBD>Q<EFBFBD>uE	<09><>U<EFBFBD>u<EFBFBD>-WT<57>3YL<1F><03>iu<69>@<40>?<3F><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>'
<01>G2}<7D>E <20>US<>A<EFBFBD><41>Yi<59>
<01>