[overlays.cinny] add custom nix commands patch for cinny

overlays/cinny/default.nix

···
+_: prev: {
+  cinny-unwrapped = prev.cinny-unwrapped.overrideAttrs (old: {
+    patches = (old.patches or [ ]) ++ [ ./nix-commands.patch ];
+  });
+}

overlays/cinny/nix-commands.patch

···
+diff --git c/src/app/features/room/RoomInput.tsx i/src/app/features/room/RoomInput.tsx
+index eb214f62..d2b43481 100644
+--- c/src/app/features/room/RoomInput.tsx
++++ i/src/app/features/room/RoomInput.tsx
+@@ -306,6 +306,12 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
+       } else if (commandName === Command.UnFlip) {
+         plainText = `${UNFLIP} ${plainText}`;
+         customHtml = `${UNFLIP} ${customHtml}`;
++      } else if (commandName === Command.NixIssue) {
++        plainText = `https://github.com/nixos/nixpkgs/issues/${plainText}`;
++        customHtml = `https://github.com/nixos/nixpkgs/issues/${customHtml}`;
++      } else if (commandName === Command.NixPR) {
++        plainText = `https://github.com/nixos/nixpkgs/pull/${plainText}`;
++        customHtml = `https://github.com/nixos/nixpkgs/pull/${customHtml}`;
+       } else if (commandName) {
+         const commandContent = commands[commandName as Command];
+         if (commandContent) {
+diff --git c/src/app/hooks/useCommands.ts i/src/app/hooks/useCommands.ts
+index bc7d2892..bb6ce6f6 100644
+--- c/src/app/hooks/useCommands.ts
++++ i/src/app/hooks/useCommands.ts
+@@ -52,6 +52,8 @@ export enum Command {
+   ConvertToRoom = 'converttoroom',
+   TableFlip = 'tableflip',
+   UnFlip = 'unflip',
++  NixIssue = 'nixi',
++  NixPR = 'nixp',
+ }
+ 
+ export type CommandContent = {
+@@ -67,6 +69,16 @@ export const useCommands = (mx: MatrixClient, room: Room): CommandRecord => {
+ 
+   const commands: CommandRecord = useMemo(
+     () => ({
++      [Command.NixPR]: {
++        name: Command.NixPR,
++        description: 'Link to nixpkgs PR.',
++        exe: async () => undefined,
++      },
++      [Command.NixIssue]: {
++        name: Command.NixIssue,
++        description: 'Link to nixpkgs issue.',
++        exe: async () => undefined,
++      },
+       [Command.Me]: {
+         name: Command.Me,
+         description: 'Send action message',