Fix achievement icons in launcher, allow opening OAuth URLs, live map docs

- Shared achievement icon catalogue; launcher resolves icon/background/border ids
- Tauri opener capability now allows http(s) URLs (fixes Discord sign-in)
- Rewrite live map docs, admin guide progression section

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DjMbLQujBHunCCu5GpsHaT

docs/admin-guide.md

@@ -83,3 +83,17 @@ Everything on this page is pushed to launchers when they start or refresh — no
 See the README's *Build your branded launcher*. Players get updates automatically: the launcher checks GitHub Releases on start and offers the new installer.
 
 **Code signing:** unsigned installers trigger a Windows SmartScreen warning ("More info → Run anyway"). To avoid it, sign the installer with a code-signing certificate (e.g. Azure Trusted Signing) — Tauri supports this via `bundle.windows.signCommand`.
+
+## Progression (quests, XP, levels)
+
+**Progression** in the sidebar controls how players advance:
+
+* **Quest limits** – how many daily and weekly quests each player is given (0 = every
+  enabled quest), and whether everyone draws their own set or shares one. Pin quests
+  on the Quests page to always include them. A player's set is stored when they first
+  open their quests for the period, so edits never swap out quests they've started.
+* **XP & levels** – the level curve (`round(base × L^exponent)`, optional max level),
+  XP per playtime hour / kill / block / message, and panel-wide multipliers that stack
+  with each server's own. Saving a new curve recalculates stored levels; nobody loses XP.
+* **Players** – search a player, then give, take, set or reset XP (global or per
+  server) or set their level. Changes are recorded in the Activity log with your reason.