nix-deps: re-expose github:manelinux/nix-deps through the hub

Adds nix-deps as an input following our nixpkgs and re-exports its
package via mkPackages (gated to native x86_64/aarch64, since its
flake only emits eachDefaultSystem and would break the s390x cross).

Also adds .gitignore for build result symlinks.

flake.lock

@@ -57,6 +57,24 @@
         "type": "github"
       }
     },
+    "flake-utils_3": {
+      "inputs": {
+        "systems": "systems_3"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "fleet-pins": {
       "inputs": {
         "nixpkgs": "nixpkgs",
@@ -125,6 +143,27 @@
         "type": "github"
       }
     },
+    "nix-deps": {
+      "inputs": {
+        "flake-utils": "flake-utils_3",
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1778863463,
+        "narHash": "sha256-TynOVZBZHiBZAjZbW2sQfaVEh5UXi4UgZ3X0pcu4nYE=",
+        "owner": "manelinux",
+        "repo": "nix-deps",
+        "rev": "5fdd0979c6254969eeb34ff49da2fa73c02972f3",
+        "type": "github"
+      },
+      "original": {
+        "owner": "manelinux",
+        "repo": "nix-deps",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1771848320,
@@ -147,6 +186,7 @@
         "flake-utils": "flake-utils_2",
         "fleet-pins": "fleet-pins",
         "hyprspace": "hyprspace",
+        "nix-deps": "nix-deps",
         "nixpkgs": [
           "fleet-pins",
           "nixpkgs-projects"
@@ -182,6 +222,21 @@
         "repo": "default",
         "type": "github"
       }
+    },
+    "systems_3": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
     }
   },
   "root": "root",