feat(slides): add persistent branding with per-slide visibility control

- Add branding overlays: logo, title, author, and footer text
- Use Reveal.js theme CSS variables for automatic color adaptation
- Inline SVGs for currentColor support on any theme
- Per-slide control via HTML comments:
  - <!-- no-branding -->: hide all elements
  - <!-- no-header -->: hide logo + title
  - <!-- no-footer -->: hide author + footer
- Fix body-level CSS selectors for proper visibility
- Add comprehensive documentation in example slides

modules/slides/README.md

@@ -16,6 +16,76 @@ Supports math, syntax highlighting, diagrams, speaker notes, and much more!
        - path: github.com/HugoBlox/kit/modules/slides
    ```
 
+## Branding & Customization
+
+### Logo and Overlays
+
+Add consistent branding across all slides by configuring `slides.branding` in your site config or slide front matter:
+
+```yaml
+# In hugo.yaml (site-wide) or slide front matter (per-deck)
+params:
+  slides:
+    branding:
+      logo:
+        filename: "logo.png"       # File in assets/media/
+        position: "top-left"       # top-left, top-right, bottom-left, bottom-right
+        width: "80px"              # Logo width
+        margin: "20px"             # Distance from edges
+      title:
+        show: true                 # Show presentation title overlay
+        text: "Short Title"        # Optional: Override auto-detected title
+        position: "bottom-left"
+      author:
+        show: true                 # Show author name overlay
+        position: "bottom-right"
+      footer:
+        text: "© 2026 Copyright"   # Footer text (e.g. copyright)
+        position: "bottom-center"  # bottom-center, bottom-left, bottom-right
+
+```
+
+### Hooks System
+
+Inject custom content into presentations without modifying module files. Create partials in your project's `layouts/_partials/hooks/` directory:
+
+| Hook | Location | Use Case |
+|------|----------|----------|
+| `slide-header/` | Top of presentation | Course code, session info |
+| `slide-footer/` | Bottom of presentation | Social handles, copyright |
+| `slide-head-end/` | End of `<head>` | Custom CSS, fonts, analytics |
+| `slide-body-end/` | End of `<body>` | Custom JS, Reveal.js plugins |
+
+Example: Create `layouts/_partials/hooks/slide-footer/social.html`:
+
+```html
+<div style="font-size: 0.5em; opacity: 0.6;">
+  @yourhandle · yoursite.com
+</div>
+```
+
+See `_example.html` files in each hook directory for more examples.
+
+## Per-Slide Visibility
+
+Control branding visibility on individual slides using HTML comments:
+
+- `<!-- no-branding -->`: Hide all branding elements (logo, header, footer)
+- `<!-- no-header -->`: Hide only the header (and logo)
+- `<!-- no-footer -->`: Hide only the footer
+
+Example:
+
+```markdown
+---
+
+<!-- no-branding -->
+
+## Full Screen Image Slide
+
+This slide will have no branding overlays.
+```
+
 ## Usage
 
 [View the documentation](https://docs.hugoblox.com/content/slides/)