New blog posts (monopam-madness, open-source-and-ai, weeknotes-2026-10),
notebook showcase with card layout and screenshots, Atom feed generator,
foundations notebook fixes, ONNX test improvements, widget interaction
tests, deploy script updates for oxcaml switch, and .gitignore for
build artifacts.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Both interactive and scrollycode extensions now check
_build/install/default/share/x-ocaml/x-ocaml.js (walking up from CWD)
before falling back to opam share. This avoids requiring 'dune install
x-ocaml' as a separate step.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Instead of requiring every .mld file to specify @x-ocaml.universe and
@x-ocaml.worker tags individually, configure the default universe path
once in dune-workspace (--config x-ocaml.universe=/_opam). The shell
emits <meta> tags from config values, and per-page @x-ocaml tags can
still override them.

Changes:
- dune-workspace: add --config x-ocaml.universe=/_opam to html_flags
- gen_rules.ml: pass --config to odoc html-generate for @site build
- odoc_jon_shell.ml: emit <meta> tags from x-ocaml.* config values
- odoc generator.ml: pass config to shell page_creator
- interactive_extension.ml: upsert meta tags (update existing or create)
- x_ocaml.ml: infer jtw backend from x-ocaml-universe meta tag
- Remove @x-ocaml.universe/@x-ocaml.worker from 14 .mld files using
the default /_opam universe
- deploy-site.sh: add dune install x-ocaml, chmod fix, widget-leaflet
- findlibish.ml: module detection fallback via jsoo runtime

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Add sidebar pipeline: compile-index → sidebar-generate → html-generate --sidebar
- jon-shell: render sidebar nav with sticky CSS layout
- Convert all {@ocamltop blocks to {@ocaml for interactive extension
- odoc-interactive-extension: handle autorun (→ run-on=load) and skip tags
- Remove package prefix from URLs (parent-id uses "." for root pages)
- Add projects/index.mld placeholder, @children_order for notebooks
- Add (prefix reference) to dune-workspace for @doc output
- Update deploy-site.sh for two-pass build (site + reference docs)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>