fix(rofi): resolve whole-swap launcher @import and page the app grid

The Apps launcher (`rofi -show drun -theme launcher`) imported
`custom.rasi` — the name HM gives *generated* themes — but a whole-swap
theme's base is deployed under its source basename (`rofi.rasi`), so the
import resolved against $HOME and rofi errored with "custom.rasi not
found" on every whole-swap theme. Make the default import track the
active base (rofi.rasi for whole-swaps, custom.rasi otherwise) and point
Boreal's own launcher.rasi at rofi.rasi.

Also give Boreal's app grid `flow: horizontal` so Down at a column's foot
pages to the next screen instead of jumping to the next column's top,
mirroring the theme-picker grid.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/home/rofi.nix

@@ -23,8 +23,9 @@ let
   # Kept separate from the base theme so a theme can give the launcher its
   # own layout (e.g. Boreal's icon grid) WITHOUT that layout leaking into
   # the text menus, which share the base theme and need a list. The default
-  # just re-imports the active theme (custom.rasi, written by HM to the same
-  # themes dir), so every other theme's launcher is byte-for-byte its list.
+  # just re-imports the active base theme (custom.rasi for generated themes,
+  # rofi.rasi for whole-swaps — see the dataFile below), so every other
+  # theme's launcher is byte-for-byte its list.
   launcherOverride = cfg.themesDir + "/${t.slug}/launcher.rasi";
   hasLauncherOverride = builtins.pathExists launcherOverride;
 
@@ -855,13 +856,17 @@ in
       '';
     };
 
-    # The launcher theme lives beside HM's generated theme
-    # (~/.local/share/rofi/themes/custom.rasi), so `@import "custom.rasi"`
-    # in the default resolves to the active theme.
+    # The launcher theme lives beside HM's active base theme, which it
+    # @imports so the default launcher is byte-for-byte that theme's list.
+    # HM names that base by its SOURCE: a generated (attrset) theme lands as
+    # custom.rasi, but a whole-swap theme (a path — themes/<slug>/rofi.rasi)
+    # keeps its basename, rofi.rasi. Import must match, or `-theme launcher`
+    # dies with "custom.rasi not found" (rofi resolves the missing import
+    # against $HOME) on every whole-swap theme.
     xdg.dataFile."rofi/themes/launcher.rasi".text =
       if hasLauncherOverride
       then builtins.readFile launcherOverride
-      else ''@import "custom.rasi"'';
+      else ''@import "${if hasRasiOverride then "rofi.rasi" else "custom.rasi"}"'';
 
     programs.rofi = {
       enable = true;

themes/boreal/launcher.rasi

@@ -2,12 +2,13 @@
  * Boreal — app-launcher override (themes/<slug>/launcher.rasi).
  * Installed to ~/.local/share/rofi/themes/launcher.rasi and used only by
  * `rofi -show drun` (the SUPER+Space / SUPER+D launcher). It inherits the
- * frosted aurora panel from the sibling custom.rasi (the active theme),
+ * frosted aurora panel from the sibling rofi.rasi (this whole-swap theme,
+ * which HM deploys under its source basename — rofi.rasi — not custom.rasi),
  * then reshapes the list into a 4×3 grid of large application icons.
  * Text menus keep the list — they don't use this theme.
  */
 
-@import "custom.rasi"
+@import "rofi.rasi"
 
 window { width: 780px; }
 
@@ -17,6 +18,10 @@ listview {
     fixed-columns: true;
     spacing: 10px;
     padding: 6px 0px 0px 0px;
+    /* Fill row-by-row so Down at a column's foot pages to the next screen
+       instead of jumping to the top of the next column (rofi's default
+       Vertical flow). Mirrors the theme-picker grid in rofi.nix. */
+    flow: horizontal;
 }
 
 element {