refactor(theme): remove 184 var() fallbacks — every one was unreachable

#2277 counted ~150 "raw colour literals bypassing the tokens". Measuring them
told a different story: 184 sat in `var(--token, #fallback)` position, and a
check against theme.css shows every one of those tokens IS declared. So the
fallbacks could not render. Not drift — vestigial.

They were also not this palette. The most common were Tailwind and Flat-UI
defaults — #6366f1 indigo, #22c55e green, #f59e0b amber, #3b82f6 blue,
#e74c3c and #27ae60 — a second, unsanctioned colour scheme sitting in the
codebase looking like the app's colours to anyone reading it.

Removing them is not tidying. #2319's lesson is that a fallback is WORSE than a
missing token: a missing token renders as nothing and someone eventually
notices, while a fallback renders something plausible forever. These 184 were
one token rename away from silently repainting the app in Tailwind. The design
token check would catch the rename — but the fallback is precisely the thing
that would make it invisible if the check were ever bypassed.

Literal count 152 -> 45, which matters beyond the number: a report that is
mostly unreachable noise is one people stop reading, and then it stops working
while still passing. What remains should be genuinely worth looking at.

Done with a paren-aware transform, not a regex — `var(--x, rgba(0,0,0,.5))`
nests parens and `[^)]+` would cut at the first one and leave `))` behind.
Verified after: every changed line is a fallback strip and nothing else, and
every var() reference still resolves.

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

frontend/src/views/ProjectView.vue

@@ -847,9 +847,9 @@ async function confirmDelete() {
 }
 .page-header-actions { display: flex; gap: 0.5rem; align-items: center; }
 .plan-title-input {
-  background: var(--color-bg, #111113);
+  background: var(--color-bg);
   color: inherit;
-  border: 1px solid var(--color-border, #2a2a2e);
+  border: 1px solid var(--color-border);
   border-radius: 6px;
   padding: 0.4rem 0.6rem;
   font: inherit;
@@ -932,8 +932,8 @@ async function confirmDelete() {
   flex-shrink: 0;
 }
 .dot-todo      { background: transparent; border: 2px solid var(--color-text-muted); }
-.dot-inprogress { background: var(--color-status-in-progress, #3b82f6); }
-.dot-done      { background: var(--color-status-done, #22c55e); }
+.dot-inprogress { background: var(--color-status-in-progress); }
+.dot-done      { background: var(--color-status-done); }
 
 .stat-todo      { background: color-mix(in srgb, var(--color-text-muted) 8%, transparent); color: var(--color-text-secondary); border-color: var(--color-border); }
 .stat-inprogress { background: color-mix(in srgb, #3b82f6 10%, transparent); color: #3b82f6; border-color: color-mix(in srgb, #3b82f6 28%, transparent); }
@@ -1066,7 +1066,7 @@ async function confirmDelete() {
 .ms-plan-rendered:hover { background: color-mix(in srgb, var(--color-primary) 4%, transparent); }
 .ms-plan-editor {
   width: 100%;
-  font-family: var(--font-mono, monospace);
+  font-family: var(--font-mono);
   font-size: 0.8rem;
   line-height: 1.5;
   padding: 0.5rem;
@@ -1133,7 +1133,7 @@ async function confirmDelete() {
   border-radius: var(--radius-sm);
 }
 .ms-action-btn:hover { background: var(--color-bg-card); color: var(--color-text); }
-.ms-action-delete:hover { color: var(--color-danger, #e74c3c); }
+.ms-action-delete:hover { color: var(--color-danger); }
 
 .ms-rename-input {
   flex: 1;
@@ -1168,8 +1168,8 @@ async function confirmDelete() {
   border-top: 3px solid;
 }
 .col-todo      { border-top-color: var(--color-border); }
-.col-inprogress { border-top-color: var(--color-status-in-progress, #3b82f6); }
-.col-done      { border-top-color: var(--color-status-done, #22c55e); }
+.col-inprogress { border-top-color: var(--color-status-in-progress); }
+.col-done      { border-top-color: var(--color-status-done); }
 
 .kanban-col-header {
   display: flex;
@@ -1230,7 +1230,7 @@ async function confirmDelete() {
   transform: translateY(-2px);
 }
 /* Priority left-border colors */
-.task-card.pri-high   { border-left-color: var(--color-danger, #e74c3c); }
+.task-card.pri-high   { border-left-color: var(--color-danger); }
 .task-card.pri-medium { border-left-color: #f59e0b; }
 .task-card.pri-low    { border-left-color: var(--color-success); }
 
@@ -1256,7 +1256,7 @@ async function confirmDelete() {
 }
 .task-card:hover .task-advance-btn { opacity: 1; }
 .task-advance-btn:hover { background: var(--color-action-primary); border-color: var(--color-action-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--done:hover { background: var(--color-success); border-color: var(--color-success); color: var(--fs-text-on-action); }
 .task-advance-btn:disabled { opacity: 0.4; cursor: default; }
 
 .priority-dot {
@@ -1265,7 +1265,7 @@ async function confirmDelete() {
   border-radius: 50%;
   flex-shrink: 0;
 }
-.dot-pri-high   { background: var(--color-danger, #e74c3c); }
+.dot-pri-high   { background: var(--color-danger); }
 .dot-pri-medium { background: #f59e0b; }
 .dot-pri-low    { background: var(--color-success); }
 
@@ -1310,7 +1310,7 @@ async function confirmDelete() {
 /* ── Modal ───────────────────────────────────────────────────── */
 .modal-overlay {
   position: fixed; inset: 0;
-  background: var(--color-overlay, rgba(0,0,0,0.45));
+  background: var(--color-overlay);
   display: flex; align-items: center; justify-content: center;
   z-index: 200;
 }