pack: add Resource Pack Overrides, revert server-push enforcement

Two changes per user direction:
- server.properties is reverted (resource-pack lines cleared, require=
  false). No more server-pushed pack -- no prompt on join, no kick if
  declined, no redundant re-download of a file the launcher already
  shipped.
- Adds resource-pack-overrides (Modrinth's gold-standard "auto-enable
  bundled resource packs" mod, 8.2M dl, client-only). The Computer
  Craft Recreated v1.2.zip already ships in the modpack manifest
  (side=client) so it's already in players' resourcepacks/ folder via
  the launcher -- RPO will be configured to default-enable it.

The RPO config (`pack/overrides/config/resourcepackoverrides-client.toml`
or similar) lands in a follow-up once we've seen the generated format.
For now this commit just gets the mod into the pack. Bumps to 0.19.4.

pack/pack.lock.json

@@ -1,7 +1,7 @@
 {
   "$schema": "Brass-and-Sigil pack.lock.json - generated, do not edit by hand unless you know what you are doing",
   "name": "Brass and Sigil",
-  "version": "0.19.3",
+  "version": "0.19.4",
   "minecraft": "1.21.1",
   "loader": {
     "type": "neoforge",
@@ -558,6 +558,17 @@
       "sha1": "18aa40e1684d1e1833ca53b2a8d7f08548bd7b5b",
       "size": 133729,
       "side": "client"
+    },
+    {
+      "source": "modrinth",
+      "slug": "resource-pack-overrides",
+      "versionId": "xf3H2eJV",
+      "version": "v21.1.0-1.21.1-NeoForge",
+      "path": "mods/ResourcePackOverrides-v21.1.0-1.21.1-NeoForge.jar",
+      "url": "https://cdn.modrinth.com/data/YsFycamt/versions/xf3H2eJV/ResourcePackOverrides-v21.1.0-1.21.1-NeoForge.jar",
+      "sha1": "42dddb70cc645a864596439ea95bd56e7a5561ed",
+      "size": 83035,
+      "side": "client"
     }
   ],
   "defaultServer": {