Initial wiki implementation

[futureshape]

Implements #1949 - leaving it as draft as there are several architectural changes yet to be decided, and I still need to test some paths, but though I'd ask or early feedback.

Created a new /wiki app to serve wiki pages. Proposing to keep that flexibility rather than assume we put all wiki pages in /about or similar.

Main UI changes

Wiki landing page

/wiki shows a list of pages and an option to create a new page, which is restricted to admins

Create page

/wiki/new creates a new page - I think it's better to do this through a form than to require a deployment for new wiki pages. Slug and title can be set independently.

View page

/wiki/<slug> renders the page using the same markdown to HTML method as the village pages. Option to edit restricted to logged in members.

❓ Do we want to restrict this to only logged in people who have a ticket?
❓ Do we want to display editor names here? (also applies to edit history)

Edit page

/wiki/<slug>/edit lets people edit the page

❓ Should we allow page title changes, and if yes maybe restrict this to admins only?
❓ Do we actually need edit summaries?

View page history

/wiki/<slug>/history shows the page history and links to comparison (diffs)

Compare page versions

/wiki/<slug>/diff/<v1>/<v2> shows a markdown diff in the standard format

Other changes

Moved render_markdown (untrusted markdown renderer) to apps/common/__init__.py together with other markdown functionality so it can be used by both villages and wiki.

TODO

• Test edit conflict functionality (implemented but not yet tried it on local dev)
• Add tests

Assisted-by: Claude Sonnet 4.6