Add seed script with 7 trees, markdown rendering, and dark mode docs

- Add comprehensive seed script with 7 troubleshooting decision trees
  - Tier 1: Password Reset, Outlook/Email, VPN, Printer Problems
  - Tier 2: Slow Computer, Network Connectivity
  - Tier 3: File Share Access Problems
- Add markdown rendering with react-markdown package
  - MarkdownContent component for session player and node editor
  - Preview toggle in description fields
- Update documentation to reflect dark mode is complete
- Update all progress tracking docs with recent changes

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/pages/TreeNavigationPage.tsx

@@ -4,6 +4,7 @@ import { treesApi, sessionsApi } from '@/api'
 import { useTreeNavigationShortcuts } from '@/hooks/useKeyboardShortcuts'
 import type { Tree, Session, DecisionRecord, TreeStructure } from '@/types'
 import { cn } from '@/lib/utils'
+import { MarkdownContent } from '@/components/ui/MarkdownContent'
 
 interface LocationState {
   sessionId?: string
@@ -380,7 +381,9 @@ export function TreeNavigationPage() {
               {currentNode.question}
             </h2>
             {currentNode.help_text && (
-              <p className="mb-4 text-sm text-muted-foreground">{currentNode.help_text}</p>
+              <div className="mb-4 text-sm text-muted-foreground">
+                <MarkdownContent content={currentNode.help_text} />
+              </div>
             )}
             <div className="mb-4 space-y-2">
               {currentNode.options?.map((option, index) => (
@@ -411,7 +414,11 @@ export function TreeNavigationPage() {
             <h2 className="mb-2 text-xl font-semibold text-card-foreground">
               {currentNode.title}
             </h2>
-            <p className="mb-4 text-muted-foreground">{currentNode.description}</p>
+            {currentNode.description && (
+              <div className="mb-4 text-muted-foreground">
+                <MarkdownContent content={currentNode.description} />
+              </div>
+            )}
             {currentNode.commands && currentNode.commands.length > 0 && (
               <div className="mb-4">
                 <p className="mb-2 text-sm font-medium text-foreground">Commands:</p>
@@ -457,7 +464,11 @@ export function TreeNavigationPage() {
             <h2 className="mb-2 text-xl font-semibold text-card-foreground">
               {currentNode.title}
             </h2>
-            <p className="mb-4 text-muted-foreground">{currentNode.description}</p>
+            {currentNode.description && (
+              <div className="mb-4 text-muted-foreground">
+                <MarkdownContent content={currentNode.description} />
+              </div>
+            )}
             {currentNode.resolution_steps && currentNode.resolution_steps.length > 0 && (
               <div className="mb-4">
                 <p className="mb-2 text-sm font-medium text-foreground">Resolution steps:</p>