docs: add TPL-008 rule and update architecture rules documentation

- Document TPL-008 (valid block names) rule
- Add common block name mistakes to quick reference
- Update statistics: 58 rules total (was 57)
- Update version to 2.4

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

docs/development/architecture-rules.md

@@ -661,6 +661,36 @@ Show empty state when lists have no items.
 </template>
 ```
 
+#### TPL-008: Use Valid Block Names
+**Severity:** Error
+
+Templates must use block names that exist in their base template. Using undefined blocks silently fails (content is not rendered).
+
+**Valid Admin Template Blocks:**
+- `title` - Page title
+- `extra_head` - Additional head content (CSS, meta tags)
+- `alpine_data` - Alpine.js component function name
+- `content` - Main page content
+- `extra_scripts` - Additional JavaScript
+
+```jinja
+{# ✅ Good - Valid block names #}
+{% block extra_scripts %}
+<script src="/static/admin/js/dashboard.js"></script>
+{% endblock %}
+
+{# ❌ Bad - Invalid block name (silently ignored!) #}
+{% block page_scripts %}
+<script src="/static/admin/js/dashboard.js"></script>
+{% endblock %}
+```
+
+**Common mistakes detected:**
+- `page_scripts` → use `extra_scripts`
+- `scripts` → use `extra_scripts`
+- `js` → use `extra_scripts`
+- `head` → use `extra_head`
+
 ---
 
 ### Jinja Macro Rules (app/templates/**/*.html)
@@ -969,6 +999,8 @@ Before committing code:
 | Business logic in endpoint | Move to service layer |
 | console.log in JS | Use `window.LogConfig.createLogger()` |
 | Missing ...data() | Add spread operator in component return |
+| Missing currentPage | Add `currentPage: 'page-name'` in component return |
+| Invalid block name | Use valid block: `extra_scripts`, `extra_head`, etc. |
 | Bare except clause | Specify exception type |
 | Raw dict return | Create Pydantic response model |
 | Template not extending base | Add `{% extends %}` or `{# standalone #}` marker |
@@ -1002,16 +1034,16 @@ All rules are defined in `.architecture-rules.yaml`. To modify rules:
 |----------|-------|--------|----------|
 | Backend | 20 | 15 | 5 |
 | Frontend JS | 7 | 6 | 1 |
-| Frontend Templates | 7 | 3 | 4 |
+| Frontend Templates | 8 | 4 | 4 |
 | Frontend Macros | 5 | 2 | 3 |
 | Frontend Components | 1 | 0 | 1 |
 | Frontend Styling | 4 | 1 | 3 |
 | Naming | 5 | 3 | 2 |
 | Security | 5 | 5 | 0 |
 | Quality | 3 | 2 | 1 |
-| **Total** | **57** | **37** | **20** |
+| **Total** | **58** | **38** | **20** |
 
 ---
 
-**Last Updated:** 2025-12-07
+**Last Updated:** 2025-12-21
-**Version:** 2.3
+**Version:** 2.4