Add configuration for Librewolf and Zen browser with privacy-focused policies

- Created Librewolf configuration in `home/programs/librewolf/system.nix` with telemetry disabled, enhanced security settings, and enforced extensions.
- Added Zen browser configuration in `home/programs/zen/default.nix` and `home/programs/zen/system.nix`, including similar privacy policies and default search engine settings.
- Introduced `hosts/home-pc/configuration.nix` for system-wide settings, including USBGuard rules and firewall configurations.
- Established `hosts/home-pc/flake.nix` to manage NixOS modules and configurations.
- Generated `hosts/home-pc/hardware-configuration.nix` for hardware-specific settings.
- Created `hosts/home-pc/home.nix` to import various user-specific applications and settings.
- Added profile picture in `hosts/home-pc/profile_picture.jpg`.
- Implemented secrets management in `hosts/home-pc/secrets/default.nix` and `hosts/home-pc/secrets/secrets.yaml` using SOPS for encryption.
- Defined user-specific variables in `hosts/home-pc/variables.nix`, including hostname, username, and locale settings.
- Added profile picture for laptop in `hosts/laptop/profile_picture.jpg`.

home/programs/zen/default.nix

@@ -0,0 +1,62 @@
+{
+  pkgs,
+  lib,
+  config,
+  ...
+}:
+{
+  programs.zen-browser = {
+    enable = true;
+
+    policies = {
+      DisableTelemetry = true;
+      DisableFirefoxStudies = true;
+      DisablePocket = true;
+
+      OfferToSaveLogins = false;
+      PasswordManagerEnabled = false;
+
+      AutofillAddressEnabled = false;
+      AutofillCreditCardEnabled = false;
+
+      DontCheckDefaultBrowser = true;
+
+      DNSOverHTTPS = {
+        Enabled = true;
+        ProviderURL = "https://dns.quad9.net/dns-query";
+        Locked = true;
+      };
+    };
+
+    profiles.default = {
+      search = {
+        force = true;
+        default = "Startpage";
+      };
+
+      settings = {
+        "browser.startup.homepage" = "https://duckduckgo.com";
+
+        "browser.newtabpage.enabled" = false;
+
+        "privacy.resistFingerprinting" = true;
+        "privacy.trackingprotection.enabled" = true;
+
+        "geo.enabled" = false;
+        "dom.webnotifications.enabled" = false;
+
+        "signon.rememberSignons" = false;
+
+        "toolkit.telemetry.enabled" = false;
+      };
+
+      extensions.packages = with pkgs.nur.repos.rycee.firefox-addons; [
+        ublock-origin
+        firefox-multi-account-containers
+        noscript
+      ];
+    };
+  };
+
+  home.sessionVariables.BROWSER = "zen";
+}