firefox: migrate extraPolicies to overrides.cfg

this fixes that the bookmarks policy in extraPolicies was breaking my bookmarks import

hosts/common/programs/firefox/default.nix

@@ -44,58 +44,59 @@ let
 
     nixExtensions = concatMap (ext: optional ext.enable ext.package) (attrValues cfg.addons);
 
-    extraPolicies = {
-      FirefoxHome = {
-        Search = true;
-        Pocket = false;
-        Snippets = false;
-        TopSites = false;
-        Highlights = false;
-      };
-      NoDefaultBookmarks = true;
-      OfferToSaveLogins = false;
-      OfferToSaveLoginsDefault = false;
-      PasswordManagerEnabled = false;
-      SearchEngines = {
-        Default = "DuckDuckGo";
-      };
-      UserMessaging = {
-        ExtensionRecommendations = false;
-        FeatureRecommendations = false;
-        SkipOnboarding = true;
-        UrlbarInterventions = false;
-        WhatsNew = false;
-      };
+    # extraPolicies: only really required if using firefox; else, easier to configure this via overrides.cfg.
+    # extraPolicies = {
+    #   FirefoxHome = {
+    #     Search = true;
+    #     Pocket = false;
+    #     Snippets = false;
+    #     TopSites = false;
+    #     Highlights = false;
+    #   };
+    #   NoDefaultBookmarks = true;
+    #   OfferToSaveLogins = false;
+    #   OfferToSaveLoginsDefault = false;
+    #   PasswordManagerEnabled = false;
+    #   SearchEngines = {
+    #     Default = "DuckDuckGo";
+    #   };
+    #   UserMessaging = {
+    #     ExtensionRecommendations = false;
+    #     FeatureRecommendations = false;
+    #     SkipOnboarding = true;
+    #     UrlbarInterventions = false;
+    #     WhatsNew = false;
+    #   };
 
-      # these were taken from Librewolf
-      AppUpdateURL = "https://localhost";
-      DisableAppUpdate = true;
-      OverrideFirstRunPage = "";
-      OverridePostUpdatePage = "";
-      DisableSystemAddonUpdate = true;
-      DisableFirefoxStudies = true;
-      DisableTelemetry = true;
-      DisableFeedbackCommands = true;
-      DisablePocket = true;
-      DisableSetDesktopBackground = false;
+    #   # these were taken from Librewolf
+    #   AppUpdateURL = "https://localhost";
+    #   DisableAppUpdate = true;
+    #   OverrideFirstRunPage = "";
+    #   OverridePostUpdatePage = "";
+    #   DisableSystemAddonUpdate = true;
+    #   DisableFirefoxStudies = true;
+    #   DisableTelemetry = true;
+    #   DisableFeedbackCommands = true;
+    #   DisablePocket = true;
+    #   DisableSetDesktopBackground = false;
 
-      # remove many default search providers
-      # XXX this seems to prevent the `nixExtensions` from taking effect
-      # Extensions.Uninstall = [
-      #   "google@search.mozilla.org"
-      #   "bing@search.mozilla.org"
-      #   "amazondotcom@search.mozilla.org"
-      #   "ebay@search.mozilla.org"
-      #   "twitter@search.mozilla.org"
-      # ];
-      # XXX doesn't seem to have any effect...
-      # docs: https://github.com/mozilla/policy-templates#homepage
-      # Homepage = {
-      #   HomepageURL = "https://uninsane.org/";
-      #   StartPage = "homepage";
-      # };
-      # NewTabPage = true;
-    };
+    #   # remove many default search providers
+    #   # XXX this seems to prevent the `nixExtensions` from taking effect
+    #   # Extensions.Uninstall = [
+    #   #   "google@search.mozilla.org"
+    #   #   "bing@search.mozilla.org"
+    #   #   "amazondotcom@search.mozilla.org"
+    #   #   "ebay@search.mozilla.org"
+    #   #   "twitter@search.mozilla.org"
+    #   # ];
+    #   # XXX doesn't seem to have any effect...
+    #   # docs: https://github.com/mozilla/policy-templates#homepage
+    #   # Homepage = {
+    #   #   HomepageURL = "https://uninsane.org/";
+    #   #   StartPage = "homepage";
+    #   # };
+    #   # NewTabPage = true;
+    # };
     # extraPrefs = ...
   }).overrideAttrs (base: {
     nativeBuildInputs = (base.nativeBuildInputs or []) ++ [
@@ -234,8 +235,13 @@ in
     fs.".librewolf/profiles.ini".symlink.target = "../.mozilla/firefox/profiles.ini";
     fs.".librewolf/managed-storage".symlink.target = "../.mozilla/firefox/managed-storage";
 
-    # TODO: this is better suited in `extraPrefs` during `wrapFirefox` call
+    # N.B.: `overrides.cfg` might be librewolf-specific -- not supported by mainline firefox.
+    # firefox does support per-profile `user.js` files which have similar functionality.
     fs.".mozilla/firefox/firefox.overrides.cfg".symlink.text = ''
+      // use `pref(...)` to force a preference
+      // use `defaultPref(...)` to allow runtime reconfiguration
+      // discover preference names via the `about:config` page
+      //
       // if we can't query the revocation status of a SSL cert because the issuer is offline,
       // treat it as unrevoked.
       // see: <https://librewolf.net/docs/faq/#im-getting-sec_error_ocsp_server_error-what-can-i-do>
@@ -273,6 +279,8 @@ in
       // - to update the static bookmarks, export via Hamburger => bookmarks => manage bookmarks => Import and Backup => Export Bookmarks To HTML
       defaultPref("browser.places.importBookmarksHTML", true);
       defaultPref("browser.bookmarks.file", "${./bookmarks.html}");
+
+      defaultPref("browser.startup.homepage", "https://uninsane.org/places");
     '';
 
     # instruct Firefox to put the profile in a predictable directory (so we can do things like persist just it).