Add Prism Launcher support and update flake lock

- Add a new home.prismlauncher module with an enable option and a
  custom package override.
- Enable Prism Launcher for the Garand‑Desktop host and remove the
  previous disabled flag.
- Add the user to the “video” group.
- Remove prismlauncher from the core packages list.
- Bump revisions and hashes for several inputs in flake.lock.
- Fix a trailing newline in the helium AppImage definition.

flake.lock

@@ -17,11 +17,11 @@
         "treefmt-nix": "treefmt-nix"
       },
       "locked": {
-        "lastModified": 1786240917,
-        "narHash": "sha256-4aAr5NeOn8fp8QBrKnfYB7N5mBZO1HjPFYpvqlCirOo=",
+        "lastModified": 1786323743,
+        "narHash": "sha256-bPT6UmXMc33Rd4rU9O8eMHhLbsJuU6ZxC2V7VDlmfms=",
         "owner": "mrshmllow",
         "repo": "affinity-nix",
-        "rev": "65610fe65b0ea94eb7913b9f37a532c83d46790f",
+        "rev": "a67e334856b7bf0ab9b5b4f38dffd436c0b8a2e5",
         "type": "github"
       },
       "original": {
@@ -138,11 +138,11 @@
         "rust-analyzer-src": "rust-analyzer-src"
       },
       "locked": {
-        "lastModified": 1785314864,
-        "narHash": "sha256-imz9J5iMNersDeQ1ymenFg35N6C2R3MCaGg2i0XCIrE=",
+        "lastModified": 1785919363,
+        "narHash": "sha256-4FDhl7ybhL5qhJw1X2IviFJ2MERnzV7X1HlJhFeSBXU=",
         "owner": "nix-community",
         "repo": "fenix",
-        "rev": "594418b2c9ea0731bee6988236ef5bfd97e81dca",
+        "rev": "d17fa5c004217ac6e51da9a8c2d2b79b0ed37109",
         "type": "github"
       },
       "original": {
@@ -181,11 +181,11 @@
       },
       "locked": {
         "dir": "pkgs/firefox-addons",
-        "lastModified": 1786248171,
-        "narHash": "sha256-ALbtZKFam+O2ONRk7XhYsXmXxmhR0Y3Bj+qZkTA8zCg=",
+        "lastModified": 1786420971,
+        "narHash": "sha256-irKN0AY5fDS96h7z3Cjp3EB7OwTJU1SeWFb1GxnFu3E=",
         "owner": "rycee",
         "repo": "nur-expressions",
-        "rev": "2e85abc79236d031845a0e2be3ebbd1759cea715",
+        "rev": "a56dfe072a448e664d208e9ed5f7f9dc9a720686",
         "type": "gitlab"
       },
       "original": {
@@ -364,11 +364,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1786031233,
-        "narHash": "sha256-TIDlLTLI1/pB7IqgjzcKQjpODQsZE2oII4XGG9B6KjI=",
+        "lastModified": 1786356609,
+        "narHash": "sha256-ou8fYz5w9yhXC8YbvvExybFIa19MyW5G/8dEPqa90hM=",
         "owner": "nix-community",
         "repo": "home-manager",
-        "rev": "7834e82588860aaf780cec1366524456a70898d7",
+        "rev": "c30c7955cec30d664a9baced6bc0112e263d4647",
         "type": "github"
       },
       "original": {
@@ -437,11 +437,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1786106723,
-        "narHash": "sha256-zDSUbpoeo/9ZmD2+wXnzxoo1+uhL8vxc0b8yuYMKYq0=",
+        "lastModified": 1786384358,
+        "narHash": "sha256-RzPPiWeUtuvymnpuEWsdtzli5w4kjZs49FqEs3/1u+I=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "f13ff45afd1bb73e640eaa08a7066dbed07e3238",
+        "rev": "2fcb964de67fcf60b43471c55d5d99e61a9ccb5a",
         "type": "github"
       },
       "original": {
@@ -489,11 +489,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1786239779,
-        "narHash": "sha256-JxVEUqGZH1PzNh4w6p0UjJRycm33uUxX1ryotRErf3A=",
+        "lastModified": 1786471551,
+        "narHash": "sha256-7NQU+Peux6ZUszNGvBEtgRhzGCxJ/RQaYP0G7cVPt2c=",
         "owner": "noctalia-dev",
         "repo": "noctalia-shell",
-        "rev": "ad647ae1bc1a119eaafb849ccce5391e9fdb0918",
+        "rev": "0b1398de6b5e245a7048d9e4c2efdf563fa14d61",
         "type": "github"
       },
       "original": {
@@ -596,11 +596,11 @@
     "rust-analyzer-src": {
       "flake": false,
       "locked": {
-        "lastModified": 1785261141,
-        "narHash": "sha256-sA+DHPejWD68mLA7gtTiHGd5T41F6W+NKf0g+ibFCW4=",
+        "lastModified": 1785889825,
+        "narHash": "sha256-U98Y5RADVCkMCbrKCFXppe6MSAi0tUTLxi3cB/SMcZI=",
         "owner": "rust-lang",
         "repo": "rust-analyzer",
-        "rev": "bec66814323579659ffd77c909b3d963af118ece",
+        "rev": "6817dd3094203c8bc4911f5799baf897623003de",
         "type": "github"
       },
       "original": {
@@ -647,11 +647,11 @@
         "tinted-zed": "tinted-zed"
       },
       "locked": {
-        "lastModified": 1786216702,
-        "narHash": "sha256-fOOmw9tUYeqWVnK2w2NiuMTmGIbluj8xiBFTTFDCcEE=",
+        "lastModified": 1786382682,
+        "narHash": "sha256-rWN1IYcqZD+rNA7PuNcMctjZgEzp83iPboeVVvgUHBM=",
         "owner": "danth",
         "repo": "stylix",
-        "rev": "b67debfd2db1eb1f0fd8740b950f598bbaf74b8f",
+        "rev": "4e328a8a98eceeb25ee19c88b36b355b400a7f68",
         "type": "github"
       },
       "original": {