feat: #3622689 Give every demo article and episode a body of its own

Issue: #3622689: The demo articles and episodes ship placeholder bodies, so every page reads the same

The problem

Every shipped article carried about 300 characters of body, and two of its three sentences were identical across all 33:

We spoke to the people closest to the work about how it came together, what changed along the way, and what they would do differently next time.

The seven episodes repeated their own summary as the body, so the episode page showed the same paragraph under "Details" and again under "Audio Transcript". On a site template that is the wrong demonstration: every article page looked identical below the headline.

The change

• 33 articles, each with its own ~265-word body in the shape of a short reported piece: an opening scene specific to that story, a named source with their role, two paragraphs of concrete detail, a pull quote, and a closing line. Three heading shapes rotate across the set.
• 7 episodes get a real question-and-answer transcript with the episode's named host.
• Dates, categories, authors and images are untouched. The editorial created dates the recipe ships are preserved.

Verification

Check	Result
unique bodies	33 of 33
body length	avg 265 words, min 228, max 350 (was 270-388 characters)
repetition	no shared paragraph appears in more than 12 of the 33
article page	12 paragraphs, 3 section headings, a pull quote, ~500 words in the main landmark
episode transcripts	~1,370 characters each
fresh install	drush si exit 0, 0 watchdog entries at severity <= 3

Still open (tracked on the issue)

• Episodes ship no field_audio_url, so the player has nothing to play; a real file or a stable public URL has to be chosen deliberately.
• Article images carry no caption or credit, which the design shows under the lede picture.

Checkpoints:

• File an issue
• Addition/Change/Update/Fix
• Testing to ensure no regression
• Automated unit testing coverage
• Automated functional testing coverage
• UX/UI designer responsibilities
• Readability
• Accessibility
• Performance
• Security
• Developer Documentation
• User Guide Documentation
• Reviewed by human
• Code review by maintainers
• Full testing and approval
• Credit contributors
• Review with the product owner
• Release notes snippet
• Release

AI-Generated: Yes