fix(dashboard): collapse empty Planning footer; Planning header matches Mission (icon/gap/title/divider)

- .planning-view-footer:empty -> display:none (no reserved space / divider band when empty); legitimate composer + start-planning footers untouched.
- Planning embedded header icon -> var(--todo), title-row gap -> space-sm, h3 -> 1.125rem/600/var(--text), border-bottom divider -> matches mission-manager__header exactly. Mission already had a single divider (no doubled line); documented the invariant.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/dashboard/app/components/MissionManager.css

@@ -54,6 +54,10 @@
 }
 
 /* ── Header ── */
+/*
+FNXC:MissionManager 2026-06-23-03:00:
+Exactly ONE divider sits under the Missions header — this header's own border-bottom. The scroll body, split, sidebar, and detail-pane add NO border-top, so there is no doubled/extra divider line below the header (verified in DOM: only this element carries a horizontal border in the header region). Planning's embedded header is matched to this single-divider treatment. Do not add a second border-top to the body/split/sidebar.
+*/
 .mission-manager__header {
   flex-shrink: 0;
   display: flex;

packages/dashboard/app/components/PlanningModeModal.css

@@ -94,17 +94,33 @@ Embedded planning must blend into the main content like Command Center: no panel
 }
 
 /*
-FNXC:Planning 2026-06-23-02:00:
-The embedded planning header now matches MissionManager's inline header (mission-manager__header--inline) EXACTLY: var(--surface) background, padding var(--space-lg) var(--space-xl), no bottom divider, and the shared 1.125rem title metric. This aligns the top header and the spacing between header and the two-pane body with Missions (previously the header used 0 0 var(--space-md) padding + a transparent fill, which read inconsistently next to Missions).
+FNXC:Planning 2026-06-23-03:00:
+The embedded planning header must be a visual SIBLING of MissionManager's inline header (mission-manager__header--inline). Matched values, copied exactly from MissionManager.css:
+- background: var(--surface), padding: var(--space-lg) var(--space-xl) (= 16px 24px)
+- a single bottom divider border-bottom: 1px solid var(--border) — Missions renders exactly ONE divider under its header (verified: only .mission-manager__header carries it; the split/sidebar add none), so Planning matches that single clean line. Previously Planning had NO divider, which read inconsistently next to Missions.
+- title: 1.125rem / 600 / var(--text) via the h3 rule below (font-weight/color come from the base .modal-header h3).
+- icon: var(--todo) tint + flex-shrink:0, identical to .mission-manager__header-icon (the shared icon-triage tint was a different brown, so it is overridden here).
+- gap icon<->title: var(--space-sm) (= 8px), identical to .mission-manager__header-title. Scoped to the embedded planning header so the shared .detail-title-row (TaskDetailModal) keeps its own 10px gap.
 */
 .planning-modal--embedded .modal-header--embedded {
   padding: var(--space-lg) var(--space-xl);
   background: var(--surface);
-  border-bottom: none;
+  border-bottom: 1px solid var(--border);
+}
+
+.planning-modal--embedded .modal-header--embedded .detail-title-row {
+  gap: var(--space-sm);
+}
+
+.planning-modal--embedded .modal-header--embedded .detail-title-row > svg {
+  color: var(--todo);
+  flex-shrink: 0;
 }
 
 .planning-modal--embedded .modal-header--embedded h3 {
   font-size: 1.125rem;
+  font-weight: 600;
+  color: var(--text);
   letter-spacing: normal;
 }
 
@@ -508,6 +524,16 @@ The New session button must look EXACTLY like Missions' primary sidebar create b
   flex-shrink: 0;
 }
 
+/*
+FNXC:Planning 2026-06-23-03:00:
+An empty footer must NOT reserve vertical space or paint its divider band. When .planning-view-footer renders with no children (e.g. the initial / no-active-session state once its action is absent), collapse it to zero so the embedded Planning view shows no dead footer band. Footers WITH content (the Start-Planning button in initial, and the .planning-actions composer in an active session) are untouched — :empty only matches when there are no element/text children.
+*/
+.planning-view-footer:empty {
+  display: none;
+  padding: 0;
+  border-top: none;
+}
+
 .planning-advanced-disclosure {
   width: 100%;
   max-width: 520px;

packages/dashboard/app/components/PlanningModeModal.tsx

@@ -1926,6 +1926,10 @@ export function PlanningModeModal({ isOpen, onClose, onTaskCreated, onTasksCreat
                 <ChevronLeft size={18} />
               </button>
             )}
+            {/*
+            FNXC:Planning 2026-06-23-03:00:
+            Header icon mirrors MissionManager's <Target size={20} className="mission-manager__header-icon" />: same size (20) and same var(--todo) tint + flex-shrink:0, applied via the scoped .planning-modal--embedded .modal-header--embedded .detail-title-row > svg rule (it overrides the shared icon-triage brown so the two headers read as siblings).
+            */}
             <Lightbulb size={20} className="icon-triage" />
             <h3>{t("planning.title", "Planning Mode")}</h3>
           </div>