planet: add gilwath feed (OCaml-filtered), disable dead dinosaure feed

Add Benjamin Thuillier's blog (gilwath.com) to the OCaml Planet. It is a
mixed OCaml/Scala blog, so publish_all is false — the scraper's caml filter
keeps only the OCaml-related posts (Discovering OCaml as a Scala Developer
parts 1-3, Building a CV page with YOCaml) and drops the pure-Scala ones.
The Atom feed parses cleanly with Syndic (7 entries).

Disable the dinosaure feed (blog.osau.re): the domain no longer resolves and
the scrape fails every day (see #3753). Following the ocaml-book/emilpriver
convention, it is disabled rather than removed so the 23 already-archived
posts keep rendering (they carry no source: frontmatter and resolve via the
source entry, so removing it would fail the data-packer build).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: cuihtlauac

data/planet-sources.yml

@@ -212,10 +212,13 @@
 - id: robur.coop
   name: Robur Cooperative
   url: https://blog.robur.coop/feed.xml
+# Feed is dead (blog.osau.re no longer resolves, see #3753); disabled so it is
+# no longer scraped, but the already-archived posts are kept.
 - id: dinosaure
   name: Romain Calascibetta
   url: https://blog.osau.re/feed.xml
   publish_all: false
+  disabled: true
 # Feed is dead (see #3753); disabled so it is no longer scraped, but the
 # already-archived posts are kept.
 - id: emilpriver
@@ -289,3 +292,8 @@
 - id: samoht
   name: Thomas Gazagnaire
   url: https://gazagnaire.org/feed.xml
+# Mixed OCaml/Scala blog; publish_all: false keeps only the caml-related posts.
+- id: gilwath
+  name: Benjamin Thuillier
+  url: https://gilwath.com/atom.xml
+  publish_all: false