chore(open-source): drop the indeedhub submodule — it breaks --recursive clones

Open-source readiness plan, Phase 2.

The `indeedhub` submodule points at a Gitea repo that is not public and carries
no known licence (the licence audit defers it: "partnership in place; license
the submodule before/at public release"). An outside developer running
`git clone --recursive` today either fails on auth or pulls unlicensed code —
a bad first five minutes with the project either way. It was never checked out
in this tree.

Removing it costs nothing, because nothing builds from it:

- `indeedhub-demo/Dockerfile` states in its own header "No submodule or local
  source needed" and clones the public GitHub mirror instead.
- Every other `indeedhub/` reference in the tree is `apps/indeedhub/` — the app
  package — which is a different path and untouched. The app itself ships as a
  container image from the registry and is unaffected.

Kept `indeedhub-demo/` rather than dropping it as the plan suggested: it is a
working, self-contained demo build with no submodule dependency, which is
exactly the shape the rest of Phase 2 is moving toward.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.gitmodules

@@ -1,3 +0,0 @@
-[submodule "indeedhub"]
-	path = indeedhub
-	url = https://source.archipelago-foundation.org/lfg2025/indeehub.git