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/extension/composer.json

@@ -0,0 +1,26 @@
+{
+    "name": "oc/flarum-museum",
+    "description": "Old-Computers.com museum integration: imports the archived visitor comments as discussions and styles the embedded threads.",
+    "type": "flarum-extension",
+    "license": "MIT",
+    "require": {
+        "flarum/core": "^2.0",
+        "flarum/tags": "^2.0",
+        "flarum/embed": "^2.0"
+    },
+    "autoload": {
+        "psr-4": {
+            "Oc\\Museum\\": "src/"
+        }
+    },
+    "extra": {
+        "flarum-extension": {
+            "title": "Old-Computers museum",
+            "icon": {
+                "name": "fas fa-landmark",
+                "backgroundColor": "#9a3412",
+                "color": "#fff"
+            }
+        }
+    }
+}