straylight: add herdr

Pin herdr v0.9.0 from the upstream flake (nixpkgs-unstable only has
0.7.1) and install it on straylight to host coding-agent terminals.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

flake.lock

@@ -96,6 +96,28 @@
         "type": "github"
       }
     },
+    "herdr": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "rust-overlay": "rust-overlay"
+      },
+      "locked": {
+        "lastModified": 1788808373,
+        "narHash": "sha256-SUYF4bbaYwNgoe498VoCUzuLPcjBLQXR0o0DWjjoSnI=",
+        "owner": "herdrdev",
+        "repo": "herdr",
+        "rev": "b99002ac99b09e00b4ca692436cb15a6b0d676f1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "herdrdev",
+        "ref": "v0.9.0",
+        "repo": "herdr",
+        "type": "github"
+      }
+    },
     "ke": {
       "inputs": {
         "nixpkgs": [
@@ -356,6 +378,7 @@
         "arca": "arca",
         "cert": "cert",
         "disko": "disko",
+        "herdr": "herdr",
         "ke": "ke",
         "kte": "kte",
         "lector": "lector",
@@ -371,6 +394,27 @@
         "sgard": "sgard"
       }
     },
+    "rust-overlay": {
+      "inputs": {
+        "nixpkgs": [
+          "herdr",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1783577481,
+        "narHash": "sha256-EWMxOWrJ031f8f/lrcEmhTRs4npw1/5N3Hcjin846c8=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "4cdea398dc491b082dccdce0fad1ed0b75fa3394",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    },
     "sgard": {
       "inputs": {
         "flake-utils": "flake-utils_2",