feat(auth)!: go fully passwordless and fix cross-check review findings

Remove password authentication everywhere; the only session doors are
passkey (WebAuthn), email OTP, in-game bind codes, QR scan-login, and
op-login vouching. Remediates the 33-finding cross-check review across
backend, CLI, panel, plugins, and docs.

Backend/CLI:
- Drop password routes and fields from account/user/onboard/auth
  handlers; align tests (new account subtests, naming reserves
  "console", op-login/onboard/qr-login test updates).
- Add migrations 0016_op_login.sql and 0017_drop_password.sql.
- Thread panel/admin hostnames from hostcfg through api.go,
  setup_panel.go, tui_root.go and tui_preflight.go instead of
  hardcoding; bootstrap.sh writes panel-hostname/admin-hostname
  into felis.toml.
- Reword breakglass and TUI copy for passwordless flows.

Panel:
- Delete the ChangePassword page and all password UI; align
  login/auth/api/types with the passwordless contract; add the
  migration and op-login approval flows.
- i18n: convert ImageBuildPage durations/status badges and
  ServerLuckPerms strings to translation keys; drop 72 orphan keys
  per locale; unify the title as "Felis - Console".

Plugins (all six rebuilt):
- Velocity waiting router returns 503 at_capacity during wake;
  MOTD/control-channel copy and config comments.
- Paper zh menu title; Limbo bind-code TTL 600s with panel_url
  preference; unified /link lines in fabric/forge/neoforge; shared
  link-client javadoc contract fixes.

Docs: openapi.yaml, sequence-diagrams.md, deploy/limbo/README.md and
plugins/README.md aligned with the implementation.

BREAKING CHANGE: migration 0017 irreversibly drops
users.password_hash and users.must_change_password; password login
cannot be restored after migrating.

plugins/neoforge/src/main/java/best/lolicon/felis/neoforge/FelisNeoForgeMod.java

@@ -74,7 +74,7 @@ public final class FelisNeoForgeMod {
             try {
                 player = source.getPlayerOrException();
             } catch (CommandSyntaxException e) {
-                source.sendFailure(Component.literal("/link can only be run by a player."));
+                source.sendFailure(Component.literal("/link 只能由玩家执行 / /link can only be run by a player."));
                 return 0;
             }
             requestAndReply(source.getServer(), player);
@@ -84,18 +84,22 @@ public final class FelisNeoForgeMod {
 
     private void requestAndReply(MinecraftServer server, ServerPlayer player) {
         UUID uuid = player.getUUID();
-        player.sendSystemMessage(Component.literal("Requesting a link code…"));
+        player.sendSystemMessage(Component.literal("正在获取绑定码… / Requesting a link code…"));
         io.submit(() -> {
             try {
                 LinkCode code = linkClient.requestCode(uuid);
-                server.execute(() -> player.sendSystemMessage(Component.literal(
-                        "Your link code: " + code.code()
-                        + "  — enter it on the web panel → Account (valid a few minutes).")));
+                server.execute(() -> {
+                    player.sendSystemMessage(Component.literal(
+                            "绑定码 / Link code: " + code.code() + "（几分钟内有效 / valid a few minutes）"));
+                    player.sendSystemMessage(Component.literal(code.panelUrl() != null
+                            ? "在此完成绑定 / Finish linking at: " + code.panelUrl()
+                            : "在网页控制台 → 账户 中输入 / Enter it on the web console → Account."));
+                });
             } catch (LinkException e) {
                 LOGGER.warn("link code request failed for {} (status={}, code={}): {}",
                         uuid, e.statusCode(), e.errorCode(), e.getMessage());
                 server.execute(() -> player.sendSystemMessage(Component.literal(
-                        "Couldn't get a link code right now. Please try again in a moment.")));
+                        "现在无法获取绑定码，请稍后再试 / Couldn't get a link code right now. Please try again in a moment.")));
             }
         });
     }