fix(ui): Disable State and ER diagrams temporarily

**Problem:**
State and ER diagrams have rendering issues and cause confusion.

**Solution:**
1. Removed from system prompt (SystemPromptConfiguration.swift)
   - Deleted 'stateDiagram' and 'erDiagram' from Mermaid types list
   - LLMs will no longer be instructed to generate these types

2. Added parser guards (MermaidParser.swift)
   - Return .unsupported for state/ER diagrams
   - Log warning when encountered
   - Prevents attempted rendering

**Impact:**
- Test file mermaid-test.json will now show diagrams #3 (class) then #5 (gantt) with #4 (state) hidden
- No more diagram numbering confusion
- No more cross-diagram contamination

**To Re-Enable:**
1. Fix rendering issues in StateDiagramRenderer.swift and ERDiagramRenderer.swift
2. Remove parser guards
3. Re-add to system prompt

**Files Modified:**
- Sources/ConfigurationSystem/SystemPromptConfiguration.swift (line 564)
- Sources/UserInterface/Chat/Mermaid/MermaidParser.swift (lines 22-26)

**Testing:**
✅ Build: PASS
⏳ User should no longer see State diagram (#4)
⏳ Class diagram should work correctly

Author: fewtarius

Sources/ConfigurationSystem/SystemPromptConfiguration.swift

@@ -561,7 +561,7 @@ private static func buildSAMSpecificPatterns() -> String {
 
     ## Data Visualization Protocol (CRITICAL)
 
-    **Mermaid Diagram Types:** flowchart, sequenceDiagram, classDiagram, stateDiagram, erDiagram, gantt, pie, barChart, journey, mindmap, timeline, quadrantChart, requirementDiagram, gitGraph, xychart-beta (bar/line charts).
+    **Mermaid Diagram Types:** flowchart, sequenceDiagram, classDiagram, gantt, pie, barChart, journey, mindmap, timeline, quadrantChart, requirementDiagram, gitGraph, xychart-beta (bar/line charts).
 
     **DECISION RULE - Mermaid vs Image Generation:**
 

Sources/UserInterface/Chat/Mermaid/MermaidParser.swift

@@ -20,9 +20,13 @@ struct MermaidParser {
         } else if trimmed.starts(with: "classDiagram") {
             return parseClassDiagram(trimmed)
         } else if trimmed.starts(with: "stateDiagram") {
-            return parseStateDiagram(trimmed)
+            // Temporarily disabled - rendering issues
+            logger.warning("State diagrams temporarily disabled")
+            return .unsupported(code)
         } else if trimmed.starts(with: "erDiagram") {
-            return parseERDiagram(trimmed)
+            // Temporarily disabled - rendering issues
+            logger.warning("ER diagrams temporarily disabled")
+            return .unsupported(code)
         } else if trimmed.starts(with: "gantt") {
             return parseGantt(trimmed)
         } else if trimmed.starts(with: "pie") {