fix: Improve text readability on light backgrounds

Fixed white/light text on white/light backgrounds across multiple pages by adding text-gray-900 classes to ensure proper contrast and readability. This addresses the issue where text was unreadable until hover/click on delegation, proposal, swap, and other pages.

Changes:
- DelegationManager: Added dark text to green-50 TabsList
- DelegateProfile: Fixed text color in blue-50 and green-50 Alert components
- ProposalWizard: Added dark text to green-50 success Alert
- Dashboard: Fixed text color in yellow-50 verification warning
- TokenSwap: Added dark text to all gray-50 and blue-50 containers (6 instances)
- DiscussionThread: Fixed markdown help card with gray-50 background
- FundingProposal: Added dark text to yellow-50 milestone warning

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/components/forum/DiscussionThread.tsx

@@ -364,9 +364,9 @@ export function DiscussionThread({ proposalId }: { proposalId: string }) {
             <Button>Post Comment</Button>
           </div>
           {showMarkdownHelp && (
-            <Card className="mt-4 p-4 bg-gray-50">
-              <p className="text-sm font-semibold mb-2">Markdown Formatting:</p>
-              <ul className="text-sm space-y-1">
+            <Card className="mt-4 p-4 bg-gray-50 text-gray-900">
+              <p className="text-sm font-semibold mb-2 text-gray-900">Markdown Formatting:</p>
+              <ul className="text-sm space-y-1 text-gray-900">
                 <li>**bold** → <strong>bold</strong></li>
                 <li>*italic* → <em>italic</em></li>
                 <li>[link](url) → <a href="#" className="text-blue-600">link</a></li>