docs: Update skeleton loader implementation from hyperscript to JavaScript

MIGRATION SUMMARY:
- Moved skeleton loader logic from hyperscript to JavaScript (main.js)
- Changed from htmx:oobAfterSwap to htmx:afterSettle event
- Changed OOB swap from innerHTML to outerHTML for proper element replacement
- Added languageSwitching flag for state tracking
- Added 100ms delay after afterSettle for final render completion

DOCUMENTATION UPDATES:
- 2-MODERN-WEB-TECHNIQUES.md: Updated skeleton loader section with

doc/3-API.md

@@ -1190,7 +1190,7 @@ curl -H "Referer: https://evil.com/" \
 **Current Configuration:**
 - **Endpoint:** `/export/pdf`
 - **Limit:** 3 requests per minute per IP
-- **Window:** 1 minute (rolling)
+- **Window:** 1 minute (rolling)
 - **Response:** 429 Too Many Requests when exceeded
 
 **Implementation:**
@@ -1266,7 +1266,7 @@ pdfRateLimiter := middleware.NewRateLimiter(5, 1*time.Hour)
 - Input validation
 - Error message sanitization (internal errors hidden)
 - Timeouts on all operations
-- Graceful shutdown
+- Graceful shutdown
 - Origin checking (prevents external hotlinking)
 - Rate limiting (PDF endpoint: 3 requests/min per IP)
 - IP-based tracking (supports reverse proxies)
@@ -1974,7 +1974,7 @@ go tool trace trace.out
 ---
 
 **Last Updated:** November 12, 2025
-**API Version:** 1.1.0
+**API Version:** 1.1.0
 **Documentation Version:** 1.1.0
 ### Support