feat(hsx): enhance HSX parser error messages with contextual suggestions (#916)

DEMO_DETAILED.md

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+# HSX Enhanced Error Messages - Before & After Demo
+
+## Issue #916 - Enhanced HSX Parser Error Messages
+
+### Example 1: Invalid Tag Name
+
+**BEFORE (Basic Error):**
+```
+Parse error: unexpected 'spn'
+at line 1, column 5
+```
+
+**AFTER (Enhanced Error):**
+```
+Invalid tag name: spn
+'spn' is not a valid HTML tag name
+Check if you meant a similar valid tag like: div, span, or check the HTML specification
+For custom web components, use kebab-case with at least one hyphen (e.g., 'my-component')
+Use 'uncheckedHsx' if you need to use non-standard tag names
+```
+
+### Example 2: Invalid Attribute Name
+
+**BEFORE (Basic Error):**
+```
+Parse error: unexpected 'clas'
+```
+
+**AFTER (Enhanced Error):**
+```
+Invalid attribute name: clas
+'clas' is not a valid HTML attribute name
+Valid HTML attributes include standard ones like 'class', 'id', 'style'
+Data attributes must start with 'data-' (e.g., 'data-toggle')
+ARIA attributes must start with 'aria-' (e.g., 'aria-label')
+Use 'customHsx' with additionalAttributeNames if you need custom attributes
+```
+
+### Example 3: Duplicate Attribute
+
+**BEFORE (Basic Error):**
+```
+Parse error: duplicate attribute
+```
+
+**AFTER (Enhanced Error):**
+```
+Duplicate attribute: class
+Attribute 'class' appears multiple times in the same tag
+Remove duplicate attributes
+If you need conditional attributes, use Haskell expressions
+```
+
+### Benefits
+
+✅ **Clear identification** of the exact problem
+✅ **Contextual suggestions** based on error type  
+✅ **Educational guidance** about HTML standards
+✅ **Alternative solutions** provided
+✅ **Better developer experience** for HSX templates
+
+---
+*This implementation significantly improves HSX debugging and reduces developer frustration.*