refactor: replace cyan accent with ember orange across entire frontend

Swap accent color from cyan (#22d3ee) to ember orange (#f97316) site-wide.
Cyan caused contrast issues and felt generic — orange brings warmth and
urgency fitting for a troubleshooting tool.

Changes:
- CSS variables: accent, accent-hover, accent-dim, accent-text, primary, ring
- Warning color shifted from amber (#fbbf24) to yellow (#eab308) for
  semantic separation from orange accent
- Brand SVGs: logo gradient updated to orange
- 50+ component files: all hardcoded cyan hex values, Tailwind cyan-*
  classes, and rgba(34,211,238,...) glow values replaced
- landing.css: all 45+ cyan references + 5 old border color fixes
- DESIGN-SYSTEM.md bumped to v5 with decisions log
- CLAUDE.md: all color references synced to charcoal palette + orange accent
- PWA theme-color meta tag updated to match sidebar (#10121a)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/pages/SessionHistoryPage.tsx

@@ -329,7 +329,7 @@ export function SessionHistoryPage() {
                   value={aiSearchInput}
                   onChange={(e) => setAiSearchInput(e.target.value)}
                   placeholder="Search sessions..."
-                  className="w-full rounded-lg border border-border bg-card pl-8 pr-3 py-1.5 text-sm text-foreground placeholder:text-muted-foreground focus:border-[rgba(6,182,212,0.3)] focus:outline-none"
+                  className="w-full rounded-lg border border-border bg-card pl-8 pr-3 py-1.5 text-sm text-foreground placeholder:text-muted-foreground focus:border-[rgba(249,115,22,0.3)] focus:outline-none"
                 />
               </div>
 
@@ -356,7 +356,7 @@ export function SessionHistoryPage() {
                 value={aiFilters.problem_domain}
                 onChange={(e) => setAiFilters((f) => ({ ...f, problem_domain: e.target.value }))}
                 title="Filter by problem domain"
-                className="rounded-lg border border-border bg-card px-3 py-1.5 text-sm text-foreground focus:border-[rgba(6,182,212,0.3)] focus:outline-none [&>option]:bg-card [&>option]:text-foreground"
+                className="rounded-lg border border-border bg-card px-3 py-1.5 text-sm text-foreground focus:border-[rgba(249,115,22,0.3)] focus:outline-none [&>option]:bg-card [&>option]:text-foreground"
               >
                 <option value="">All domains</option>
                 <option value="Active Directory">Active Directory</option>
@@ -396,7 +396,7 @@ export function SessionHistoryPage() {
                   value={aiFilters.date_from}
                   onChange={(e) => setAiFilters((f) => ({ ...f, date_from: e.target.value }))}
                   title="From date"
-                  className="rounded-lg border border-border bg-card px-3 py-1.5 text-sm text-foreground focus:border-[rgba(6,182,212,0.3)] focus:outline-none [color-scheme:dark]"
+                  className="rounded-lg border border-border bg-card px-3 py-1.5 text-sm text-foreground focus:border-[rgba(249,115,22,0.3)] focus:outline-none [color-scheme:dark]"
                 />
                 <span className="text-xs text-muted-foreground">to</span>
                 <input
@@ -404,7 +404,7 @@ export function SessionHistoryPage() {
                   value={aiFilters.date_to}
                   onChange={(e) => setAiFilters((f) => ({ ...f, date_to: e.target.value }))}
                   title="To date"
-                  className="rounded-lg border border-border bg-card px-3 py-1.5 text-sm text-foreground focus:border-[rgba(6,182,212,0.3)] focus:outline-none [color-scheme:dark]"
+                  className="rounded-lg border border-border bg-card px-3 py-1.5 text-sm text-foreground focus:border-[rgba(249,115,22,0.3)] focus:outline-none [color-scheme:dark]"
                 />
               </div>
 
@@ -564,7 +564,7 @@ export function SessionHistoryPage() {
                           session.outcome === 'escalated' && 'bg-blue-500/20 text-blue-300',
                           session.outcome === 'unresolved' && 'bg-rose-500/20 text-rose-300',
                           session.outcome === 'cancelled' && 'bg-zinc-500/20 text-zinc-300',
-                          session.outcome === 'resolved_externally' && 'bg-cyan-500/20 text-cyan-300',
+                          session.outcome === 'resolved_externally' && 'bg-orange-500/20 text-orange-300',
                           !session.outcome && 'bg-accent text-muted-foreground'
                         )}
                       >
@@ -647,7 +647,7 @@ export function SessionHistoryPage() {
                         value={closeOutcome}
                         onChange={(e) => setCloseOutcome(e.target.value as SessionOutcome)}
                         title="Session outcome"
-                        className="w-full rounded-lg border border-border bg-card px-3 py-2 text-sm text-foreground focus:border-[rgba(6,182,212,0.3)] focus:outline-none mb-3"
+                        className="w-full rounded-lg border border-border bg-card px-3 py-2 text-sm text-foreground focus:border-[rgba(249,115,22,0.3)] focus:outline-none mb-3"
                       >
                         <option value="">Select outcome...</option>
                         <option value="resolved">Resolved</option>
@@ -664,7 +664,7 @@ export function SessionHistoryPage() {
                         onChange={(e) => setCloseNotes(e.target.value)}
                         rows={2}
                         placeholder="Add closure notes..."
-                        className="w-full rounded-lg border border-border bg-card px-3 py-2 text-sm text-foreground placeholder:text-muted-foreground focus:border-[rgba(6,182,212,0.3)] focus:outline-none resize-none mb-3"
+                        className="w-full rounded-lg border border-border bg-card px-3 py-2 text-sm text-foreground placeholder:text-muted-foreground focus:border-[rgba(249,115,22,0.3)] focus:outline-none resize-none mb-3"
                       />
 
                       <div className="flex items-center justify-end gap-2">