feat(avatar): NMSR skin renderer at avatar.${BASE_DOMAIN}, Drasl-backed

Add NMSR-as-a-Service (NickAcPT/nmsr-rs) rendering players' skins/avatars,
sourced from Drasl instead of Mojang.

- docker/nmsr/Dockerfile     build from source, pinned to commit 948ba4bc027b
                             (ears feature, lavapipe software Vulkan)
- nmsr/config.toml.tmpl       [mojank] -> http://auth.${BASE_DOMAIN}; Drasl
                              serves the Mojang-compatible routes at its bare
                              BaseURL and embeds absolute skin URLs that NMSR
                              fetches directly. allow_offline_mode_uuids=true.
- docker-compose.nmsr.yml     nmsr service (build), host bind 127.0.0.1:9898
                              only, config mount; mounts the caddy avatar snippet
- caddy/conf.d/40-avatar.caddy avatar.${BASE_DOMAIN} -> reverse_proxy nmsr:8080
- nginx-front + LE_SUBDOMAINS  public TLS vhost (HSTS) + cert for avatar
- render-config.sh / .gitignore render + ignore nmsr/config.toml

Skin resolution stays internal over mcnet (caddy alias -> drasl), no public
round-trip.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

nmsr/config.toml.tmpl

@@ -0,0 +1,37 @@
+# NMSR-aas config — renders to nmsr/config.toml (gitignored) via
+# tooling/render-config.sh. Only ${BASE_DOMAIN} is substituted.
+#
+# Skins come from Drasl, NOT Mojang. Drasl exposes Mojang-compatible routes at
+# the bare BaseURL:
+#   session_server     -> {url}/session/minecraft/profile/{uuid}
+#   mojang_api_server  -> {url}/users/profiles/minecraft/{name}
+# and embeds absolute skin URLs (http://auth.${BASE_DOMAIN}/web/texture/skin/…)
+# in the profile, which NMSR fetches directly (textures_server is only a
+# fallback). NMSR resolves auth.${BASE_DOMAIN} internally over the docker
+# network (caddy holds the mcnet alias → drasl), so no public round-trip.
+
+[server]
+address = "0.0.0.0"
+port = 8080
+
+[caching]
+cleanup_interval = "1h"
+resolve_cache_duration = "15m"
+texture_cache_duration = "48h"
+
+[caching.cache_biases]
+
+[mojank]
+# Point every Mojang endpoint at Drasl (internal, plain http via the caddy alias).
+session_server    = "http://auth.${BASE_DOMAIN}"
+textures_server   = "http://auth.${BASE_DOMAIN}"
+mojang_api_server = "http://auth.${BASE_DOMAIN}"
+session_server_rate_limit = 10
+# This is an offline-mode (authlib-injector) server — Drasl issues v3 offline
+# UUIDs, so they must be accepted.
+allow_offline_mode_uuids = true
+use_dashless_uuids = false
+
+[rendering]
+sample_count = 1
+use_smaa = true