semantic HTML: apropos.php and licence.php (TODO section V & VI)

apropos.php:
- Remove redundant <div class="apropos-left"> wrapper; prose div is now a direct
  grid child
- <div class="apropos-description apropos-page-content"> → <div class="prose">
  (single canonical class for Markdown-rendered content)
- <div class="apropos-right"> → <aside class="apropos-aside"> (supplementary info
  landmark; contacts and credits are secondary to the main description)
- Three bare <div> wrappers inside the aside → <section> (erg link, Contacts, Crédits)
- Three <div class="apropos-contact"> entries → <address> with font-style:normal
  override; <span class="apropos-contact-name"> → <strong>;
  <span class="apropos-contact-email"> → <a href="mailto:…">
  Removes classes: apropos-left, apropos-right, apropos-contact, apropos-contact-name,
  apropos-contact-role, apropos-contact-email, apropos-description, apropos-page-content

licence.php:
- <div class="apropos-description apropos-page-content apropos-single"> →
  <div class="prose apropos-single"> (consistent with apropos.php rename)

apropos.css:
- Rename .apropos-description / .apropos-page-content → .prose; merge all prose
  content rules under the single .prose selector
- Rename .apropos-right → .apropos-aside; remove .apropos-left (empty rule)
- Replace .apropos-contact, .apropos-contact-name etc. with element selectors:
  .apropos-aside address, .apropos-aside address strong,
  .apropos-aside address span, .apropos-aside address a
- Update responsive blocks to reference .prose instead of .apropos-description

TODO.md

@@ -688,33 +688,31 @@ The design does **not** need to change - only the vocabulary of the markup.
 
 ### V - `public/apropos.php`
 
-- [ ] **`<div class="apropos-layout">`** - two-column grid. Replace with `<div>` kept but the
+- [x] **`<div class="apropos-layout">`** - two-column grid. Replace with `<div>` kept but the
       children are semantic: left is the main content, right is supplementary.
       Left `<div class="apropos-left">` → remove (redundant wrapper around already-styled content).
-      Right `<div class="apropos-right">` → `<aside>` (contacts, credits = supplementary info).
+      Right `<div class="apropos-right">` → `<aside class="apropos-aside">` (contacts, credits = supplementary info).
 
-- [ ] **`<div class="apropos-description apropos-page-content">`** inside the left col -
+- [x] **`<div class="apropos-description apropos-page-content">`** inside the left col -
       the Parsedown output already generates `<p>`, `<h1>`-`<h3>`, `<ul>` etc.
       The wrapping `<div>` is only needed for the `.apropos-page-content` scoped CSS rules.
       Keep it but as a single class - `<div class="prose">` - and scope all Markdown content
       styles under `.prose`. This is the standard prose-container pattern.
 
-- [ ] **`<div class="apropos-contact">`** - each contact entry. Replace with `<address>`:
+- [x] **`<div class="apropos-contact">`** - each contact entry. Replace with `<address>`:
       the HTML spec defines `<address>` for contact information related to the document or section.
       Each contact is literally an address entry. `<span class="apropos-contact-name">` →
-      `<strong>`, `<span class="apropos-contact-role">` → plain text or `<span>`,
+      `<strong>`, `<span class="apropos-contact-role">` → plain text `<span>`,
       `<span class="apropos-contact-email">` → `<a href="mailto:...">`. Three classes removed.
 
-- [ ] **Outer `<div>` wrappers around each section in `.apropos-right`** (`<div><h2>...</h2></div>`,
-      `<div><h2>Contacts</h2>...</div>`, `<div><h2>Crédits</h2>...</div>`) - replace each with
-      `<section>`. Remove the anonymous `<div>` wrappers; CSS targets `aside section > h2`.
+- [x] **Outer `<div>` wrappers around each section in `.apropos-right`** (`<div><h2>...</h2></div>`,
+      `<div><h2>Contacts</h2>...</div>`, `<div><h2>Crédits</h2>...</div>`) - replaced with
+      `<section>`. CSS targets `aside section > h2`.
 
 ### VI - `public/licence.php`
 
-- [ ] **`<div class="apropos-right"></div>`** - always-empty right column. Remove entirely; the
-      `licence.php` page is full-width content. Update `licence.php` to not use `.apropos-layout`
-      at all - just `<main class="apropos-main"><div class="prose">...</div></main>`.
-      No class changes needed to `apropos.css`; the layout simply is not applied.
+- [x] **`<div class="apropos-right"></div>`** - always-empty right column. Removed entirely;
+      `licence.php` uses `<div class="prose apropos-single">` without the two-column layout.
 
 ### VII - Summary of class deletions enabled by semantic changes