Reorganize podcast structure

[nomeata]

This fixes #41.

Summary and justification of change:

• The index page of podcasts is trimmed down: Only title and summary.
  In particular, no player. Having the browser load a player for every
  episode will probably be quite sluggish as we grow more episodes.

• Not even an embedded player for the latest episode, as suggested by
  Andres. This way I want to prevent people who listen to the episode
  there to then share a non-permanent link to /podcasts. By guiding
  them to the per-episode page, they’ll have a permanent URL when they
  are listening to the episode.

• Per-episode pages. The main purpose of this refactor. This gives us
  stable URLs for each episode, which is important for sharing, and
  also for googlability.

• The transcript is part of that page; no separate transcript page.
  Yes, the page gets long, but that’s ok, there is nothing below.
  Advantages:

  • less pages
  • search engines will lead people to the episode page directly, so
    better discoverabiliy
  • people can scroll and read while they are listening to the episode;
    no need to open a new tab (or click on the link which then stops
    the player)

  The transcript could be in a collapsed section; leaving this for
  future refinement.

• Shuffling of the source files in pdocast/:

  • all files for one episode in one directory, no further nesting

  • links and transcripts are both separate markdown files, both
    optional

  • this way, the description becomes the “body” (in the Hakyll sense)
    of the index.markdown file. This means we can use markdown markup
    there too, if we want to.

• Tweaked styling, stealing some ideas from the “affiliates” page, in
  particular the bar on the left. Horrible cargo-culting of tailwind
  CSS classes – I will be happy when someone polishes that a bit further

• Loading the extra pages via the hakyll context the way I do may or
  may not be idiomatic hakyll code. Also here: refactoring welcome.

[tfausak]

😍