Forum integration: Flarum extension, local test stack, embedded comments

- forum/extension: oc:import command (archived comments -> one thread per
  machine) and embed styling
- forum/docker: local Flarum 2 test stack
- site: optional params.forum.url adds a Forum menu entry and shows the
  machine thread in the Comments tab

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YDRjtmAiNpo5mK5N3d7QwZ

forum/README.md

@@ -0,0 +1,71 @@
+# Forum and comments (Flarum)
+
+The forum is a separate PHP application ([Flarum](https://flarum.org/) 2, PHP 8.3+, MariaDB or
+MySQL). It is not part of the static build: the site only links to it and shows its threads in a
+frame.
+
+| Path | Role |
+|---|---|
+| `extension/` | Flarum extension `oc/flarum-museum`: the `oc:import` command and the look of embedded threads |
+| `docker/`, `docker-compose.yml` | local test forum |
+| `import/` | not versioned: `machines.json` (export from the extraction repo) and `forum.json` (thread map) |
+
+## How comments work
+
+- `../oc/scripts/06_forum.py` writes `import/machines.json`: one entry per machine with its
+  archived comments, oldest first.
+- `php flarum oc:import` creates one discussion per machine: an opening post linking to the
+  museum page, then one post per archived comment, all by the user `Archive`, with the original
+  author and date at the top of each post and the original date as the post date. Discussions go
+  under three tags (Computers, Consoles, Pongs) that are hidden from "All discussions".
+- The command records what it imported (table `oc_threads`) and skips it on later runs, so it
+  can be run again when new machines arrive. It writes the map machine → discussion to
+  `forum.json`.
+- Copied to `../data/forum.json`, that map makes `make content` give every machine a Comments
+  tab pointing at its thread (`forum_thread` in the page front matter); the old comments are
+  then no longer written into the pages.
+- With `params.forum.url` set, the Comments tab shows `<forum>/embed/<id>` (Flarum's Embed
+  extension) in a frame that follows the height of the thread.
+
+## Local test
+
+    make forum-up        # http://localhost:8081, admin / adminadmin (first start takes a minute)
+    make forum-import    # export + import; safe to repeat
+
+To see it in the site, copy `forum/import/forum.json` to `data/forum.json`, run `make content`,
+and build with `HUGO_PARAMS_FORUM_URL=http://localhost:8081 hugo server`. Do not commit a
+`data/forum.json` made from the test forum: its thread numbers are not those of the real one.
+
+## Server install (outline)
+
+The forum must live **outside** the folder `make deploy` writes to (that folder is synchronised
+with deletion). On the test server: `web/oldcomputers-forum/`, next to `web/oldcomputers/`.
+
+1. PHP 8.3 or newer with curl, dom, fileinfo, gd, json, mbstring, openssl, pdo_mysql, tokenizer,
+   zip; an empty database and a user for it.
+2. `composer create-project flarum/flarum oldcomputers-forum "^2.0"`, then in that folder
+   `composer require flarum/embed "^2.0"`.
+3. Web server: requests that are not files go to `public/index.php`, and nothing outside `public/`
+   is served. Flarum ships rules for Apache (`public/.htaccess`) and nginx (`.nginx.conf`); a
+   sub-folder install is described in the Flarum documentation ("Customizing paths").
+4. Open the forum address and finish the installer (database, administrator account).
+5. Copy `extension/` to `packages/oc-museum/` in the forum folder, then:
+
+       composer config repositories.oc path "packages/*"
+       composer require "oc/flarum-museum:*@dev"
+       php flarum migrate
+       php flarum extension:enable flarum-tags
+       php flarum extension:enable flarum-embed
+       php flarum extension:enable oc-museum
+
+6. In the admin panel: e-mail settings (registration confirms addresses by e-mail), and a spam
+   filter extension. Schedule a database dump.
+7. Import: copy `import/machines.json` to the server and run
+
+       php flarum oc:import machines.json --site-url=https://example.org/oldcomputers --map=forum.json
+
+   then bring `forum.json` back as `data/forum.json`, set `params.forum.url`, `make content`,
+   `make deploy`.
+
+The forum and the site should share one domain: logging in from the embedded thread relies on
+the forum's cookie, which browsers restrict across domains.