feat(themes): executive-ivory — the light half of the executive pair

Second exclusive pair (see 0ba1762 for the batch). Executive Ivory is
the slate boardroom at 9 AM: the night skyline traded for paper, print
and daylight. Warm ivory base (#F2F0E9), ink text (12.1:1 AAA), the
steel blue deepened to letterhead weight (#2F5FBF, 5.25:1 as text),
JetBrainsMono + slate's exact 5/12/2/10 geometry. Assets: the same
solid edge-to-edge strip identity (ink on ivory, accent underline on
the active workspace), rofi, btop, and a line-web wallpaper that
mirrors slate's geometry in silver-on-paper with sparse blue threads.

Verification: V2, same evidence set as 0ba1762 (all targeted checks
green on this tree; theme-shot VM desktop + menu viewed — strip,
underline, paper panel all render legibly; screenshots in
/nix/store/5883sqfz...theme-shot-executive-ivory). Preview is the
480x270 VM render. V3 pending per the batch HARDWARE-QUEUE entry.

Design on Fable; asset port by a Sonnet subagent from the
executive-slate sources; reviewed on Fable.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

themes/executive-ivory/rofi.rasi

@@ -0,0 +1,125 @@
+/**
+ * Executive Ivory — rofi whole-swap (themes/<slug>/rofi.rasi).
+ * Identity: a flat, sharp-cornered "control panel". No zebra, no glow —
+ * a solid ivory window, a recessed surface inputbar, and one accent edge
+ * marking the selected row. The `configuration {}` block is omitted on
+ * purpose — modi/terminal/show-icons come from modules/home/rofi.nix.
+ * Element structure mirrors the generated theme so the theme-grid
+ * picker's per-invocation -theme-str (vertical cards) still lays out.
+ */
+
+* {
+    base:      #F2F0E9;
+    surface:   #E8E5DB;
+    overlay:   #ABA898;
+    text:      #252D3B;
+    subtext:   #4A5568;
+    muted:     #767E8D;
+    accent:    #2F5FBF;
+    accentAlt: #46689E;
+
+    font: "Inter 13";
+    background-color: transparent;
+    text-color: @text;
+}
+
+window {
+    background-color: @base;
+    border: 1px;
+    border-color: @overlay;
+    border-radius: 4px;
+    width: calc( 84ch min 65% );
+    location: center;
+    anchor: center;
+    padding: 12px;
+}
+
+mainbox {
+    background-color: transparent;
+    children: [ inputbar, message, listview ];
+    spacing: 10px;
+}
+
+inputbar {
+    children: [ prompt, entry ];
+    background-color: @surface;
+    text-color: @text;
+    border: 1px;
+    border-color: @overlay;
+    border-radius: 4px;
+    padding: 10px 14px;
+    spacing: 10px;
+}
+
+prompt { text-color: @accent; }
+
+entry {
+    text-color: @text;
+    cursor: text;
+    placeholder: "Type to filter…";
+    placeholder-color: @muted;
+}
+
+listview {
+    background-color: transparent;
+    columns: 1;
+    lines: 8;
+    dynamic: true;
+    scrollbar: true;
+    spacing: 4px;
+    padding: 4px 0px 0px 0px;
+}
+
+element {
+    background-color: transparent;
+    text-color: @text;
+    orientation: horizontal;
+    border-radius: 4px;
+    padding: 9px 14px;
+    spacing: 12px;
+}
+
+element normal.normal,
+element alternate.normal {
+    background-color: transparent;
+}
+
+/* The one highlight: a solid accent-tinted row with an accent edge. */
+element selected.normal {
+    background-color: #2F5FBF26;
+    text-color: @text;
+    border: 0px 0px 0px 3px;
+    border-color: @accent;
+}
+
+element-icon {
+    background-color: transparent;
+    size: 36px;
+    cursor: inherit;
+}
+
+element-text {
+    background-color: transparent;
+    text-color: inherit;
+    highlight: bold;
+    vertical-align: 0.5;
+}
+
+message { padding: 0px; }
+
+textbox {
+    background-color: @surface;
+    text-color: @text;
+    border: 1px;
+    border-color: @overlay;
+    border-radius: 4px;
+    padding: 9px 14px;
+}
+
+scrollbar {
+    width: 4px;
+    handle-width: 4px;
+    handle-color: @accent;
+    background-color: @surface;
+    border: 0px;
+}