Finish the move off weblorgmigrate-to-orgo

Remove what the migration left behind, then cut build.py down to the work
orgo does not do: 443 lines to 168.

- Delete publish.el and theme/templates/, superseded by content/orgo.toml
  and content/templates/. theme/static/ stays; orgo publishes it as assets.
- Drop the tag builder, the org-source copy, and the helpers that only fed
  them. orgo generates /tags/ and a page per tag from a collection.
- Rewrite the README and the migration-era comments that explained the
  config by pointing at what weblorg used to do.
- Serve styles.css as authored. Minifying 1KB of CSS saved 52 bytes over
  the wire once compressed, which did not pay for a build step and a
  toolchain dependency.
- Stop wiping the output directory. The .orgo-cache.json inside it is what
  makes a build incremental, and orgo already prunes outputs whose source
  is gone and re-emits any that are missing. Production keeps .build/ and
  development gets .build-dev/, because production rewrites image URLs in
  the output and a shared directory would let one environment reuse pages
  rendered for the other.

An incremental build is byte-identical to a clean one, and the site output
is unchanged apart from the /uses/ stack row.

1 files changed, 2 insertions, 3 deletions

diff --git a/content/templates/home.html b/content/templates/home.html
index 6d280ee..6a2cf33 100644
--- a/content/templates/home.html
+++ b/content/templates/home.html
@@ -1,9 +1,8 @@
 {# The home page: authored prose plus the most recent posts.
 
    A generated page, so it has no source .org file — `pages` holds the blog collection's
-   entries, newest first, and the prose lives here. This mirrors what weblorg's
-   theme/templates/index.html does today, including its bare <title>: the home page is
-   "cleberg.net" and not "cleberg.net - cleberg.net". #}
+   entries, newest first, and the prose lives here. The <title> is bare on purpose: the
+   home page is "cleberg.net" and not "cleberg.net - cleberg.net". #}
 {% extends "base.html" %}
 {% block subtitle %}{% endblock %}
 {% block main %}