fix(theme): text on a filled colour needs its own token — the old one inverts

76 hardcoded `color: #fff` now resolve to --fs-text-on-action, a new token
that is parchment in BOTH modes.

The design system said they should supersede to --fs-text-primary, on the
recorded reasoning that "there is no 'text on action' colour, there is just the
text colour." That is true on dark and wrong on light. --fs-text-primary
inverts to #14171A; the surfaces underneath it do not invert at all — every one
of these 76 sits on an action colour, a semantic colour, the accent, or the CTA
gradient, all of which hold a single value across modes.

Sweeping as recorded would have put obsidian text on moss green: roughly 2.4:1,
against a house style whose stated floor is WCAG AA. It would have looked
correct to me, because I checked it in the mode where it was correct.

--color-accent-fg had the same defect independently and is repointed too.

The token check now reports zero superseded literals, down from 30 files, and
raw colour literals drop 246 -> 169.

Closes #2275.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UaYUaouG9jjhATyuxCKrQs

frontend/src/views/ProjectView.vue

@@ -879,7 +879,7 @@ async function confirmDelete() {
   gap: 0.35rem;
   padding: 0.45rem 1rem;
   background: var(--gradient-cta);
-  color: #fff;
+  color: var(--fs-text-on-action);
   border: none;
   border-radius: var(--radius-sm);
   font-size: 0.875rem;
@@ -888,14 +888,14 @@ async function confirmDelete() {
   box-shadow: var(--glow-cta);
   transition: box-shadow 0.15s, opacity 0.15s;
 }
-.btn-workspace:hover { box-shadow: var(--glow-cta-hover); opacity: 0.95; color: #fff; }
+.btn-workspace:hover { box-shadow: var(--glow-cta-hover); opacity: 0.95; color: var(--fs-text-on-action); }
 
 /* Share: Bronze action-secondary — alternate path */
 .btn-share {
   padding: 0.4rem 0.8rem;
   background: var(--color-action-secondary);
   border: none;
-  color: #fff;
+  color: var(--fs-text-on-action);
   border-radius: var(--radius-sm);
   cursor: pointer;
   font-size: 0.85rem;
@@ -917,7 +917,7 @@ async function confirmDelete() {
   font-family: inherit;
   transition: background 0.15s, color 0.15s;
 }
-.btn-danger-outline:hover { background: var(--color-action-destructive); color: #fff; }
+.btn-danger-outline:hover { background: var(--color-action-destructive); color: var(--fs-text-on-action); }
 
 .error-msg { color: var(--color-danger); font-size: 0.9rem; }
 
@@ -1065,7 +1065,7 @@ async function confirmDelete() {
 .btn-save-panel {
   padding: 0.45rem 0.9rem;
   background: var(--color-action-primary);
-  color: #fff;
+  color: var(--fs-text-on-action);
   border: none;
   border-radius: var(--radius-sm);
   cursor: pointer;
@@ -1151,7 +1151,7 @@ async function confirmDelete() {
 .btn-ms-confirm {
   padding: 0.3rem 0.65rem;
   background: var(--color-action-primary);
-  color: #fff;
+  color: var(--fs-text-on-action);
   border: none;
   border-radius: var(--radius-sm);
   cursor: pointer;
@@ -1165,7 +1165,7 @@ async function confirmDelete() {
   padding: 0.3rem 0.65rem;
   background: var(--color-action-secondary);
   border: none;
-  color: #fff;
+  color: var(--fs-text-on-action);
   border-radius: var(--radius-sm);
   cursor: pointer;
   font-size: 0.78rem;
@@ -1224,7 +1224,7 @@ async function confirmDelete() {
   cursor: pointer;
   border: 1px solid var(--color-border);
 }
-.ms-plan-actions .btn-primary { background: var(--color-primary); color: #fff; border-color: var(--color-primary); }
+.ms-plan-actions .btn-primary { background: var(--color-primary); color: var(--fs-text-on-action); border-color: var(--color-primary); }
 .ms-plan-actions .btn-primary:disabled { opacity: 0.6; cursor: default; }
 .ms-plan-actions .btn-secondary { background: var(--color-bg-card); color: var(--color-text); }
 
@@ -1393,8 +1393,8 @@ async function confirmDelete() {
   line-height: 1;
 }
 .task-card:hover .task-advance-btn { opacity: 1; }
-.task-advance-btn:hover { background: var(--color-primary); border-color: var(--color-primary); color: #fff; }
-.task-advance-btn--done:hover { background: var(--color-success, #22c55e); border-color: var(--color-success, #22c55e); color: #fff; }
+.task-advance-btn:hover { background: var(--color-primary); border-color: var(--color-primary); color: var(--fs-text-on-action); }
+.task-advance-btn--done:hover { background: var(--color-success, #22c55e); border-color: var(--color-success, #22c55e); color: var(--fs-text-on-action); }
 .task-advance-btn:disabled { opacity: 0.4; cursor: default; }
 
 .priority-dot {
@@ -1475,7 +1475,7 @@ async function confirmDelete() {
   font-family: inherit;
 }
 .modal-btn:hover { background: var(--color-bg); }
-.modal-btn-danger { background: var(--color-action-destructive); border-color: var(--color-action-destructive); color: #fff; }
+.modal-btn-danger { background: var(--color-action-destructive); border-color: var(--color-action-destructive); color: var(--fs-text-on-action); }
 .modal-btn-danger:hover { background: var(--color-action-destructive-hover); border-color: var(--color-action-destructive-hover); }
 
 /* ── Skeleton ────────────────────────────────────────────────── */