Initial commit: Brass & Sigil monorepo

Self-hosted Minecraft modpack distribution + administration system.

- launcher/  Avalonia 12 desktop client; single-file win-x64 publish.
             Microsoft auth via XboxAuthNet, manifest+SHA-1 mod sync,
             portable install path, sidecar settings.
- server/    brass-sigil-server daemon (.NET 8, linux-x64). Wraps the
             MC subprocess, embedded Kestrel admin panel with cookie
             auth + rate limiting, RCON bridge, scheduled backups,
             BlueMap CLI integration with player markers + skin proxy,
             friend-side whitelist request flow, world wipe with seed
             selection (keep current / random / custom).
- pack/      pack.lock.json (Modrinth + manual CurseForge entries),
             data-only tweak source under tweaks/, build outputs in
             overrides/ (gitignored).
- scripts/   Build-Pack / Build-Tweaks / Update-Pack / Check-Updates
             plus Deploy-Brass.ps1 unified one-shot deploy with
             version-bump pre-flight and daemon-state detection.

pack/tweaks/brassandsigil-tweaks/data/brassandsigil_tweaks/lithostitched/worldgen_modifier/skylands_end_stone.json

@@ -0,0 +1,6 @@
+{
+  "type": "lithostitched:add_features",
+  "biomes": "#terralith:skylands",
+  "features": "brassandsigil_tweaks:skylands_end_stone_ore",
+  "step": "underground_ores"
+}

pack/tweaks/brassandsigil-tweaks/data/brassandsigil_tweaks/worldgen/configured_feature/skylands_end_stone_ore.json

@@ -0,0 +1,18 @@
+{
+  "type": "minecraft:ore",
+  "config": {
+    "discard_chance_on_air_exposure": 0.0,
+    "size": 6,
+    "targets": [
+      {
+        "target": {
+          "predicate_type": "minecraft:tag_match",
+          "tag": "minecraft:stone_ore_replaceables"
+        },
+        "state": {
+          "Name": "minecraft:end_stone"
+        }
+      }
+    ]
+  }
+}

pack/tweaks/brassandsigil-tweaks/data/brassandsigil_tweaks/worldgen/placed_feature/skylands_end_stone_ore.json

@@ -0,0 +1,16 @@
+{
+  "feature": "brassandsigil_tweaks:skylands_end_stone_ore",
+  "placement": [
+    { "type": "minecraft:count", "count": 3 },
+    { "type": "minecraft:in_square" },
+    {
+      "type": "minecraft:height_range",
+      "height": {
+        "type": "minecraft:uniform",
+        "min_inclusive": { "absolute": 200 },
+        "max_inclusive": { "absolute": 250 }
+      }
+    },
+    { "type": "minecraft:biome" }
+  ]
+}