feat(landing): rework — es default, 2-step join, roster + account polish

- Default language Spanish at root /, English moves to /en/ (eu unchanged):
  getStaticPaths {lang:undefined}->es + LANG_*_PATH maps swapped in ui.ts.
- Section order: hero -> join -> status -> members -> mods -> features.
- Join flow 3 -> 2 steps (drop the Connect/IP step; launcher handles the
  address). Remove the hero IP CopyChip. Header CTA renamed Play/Jugar/Jolastu
  and gains Register + Login links on all four pages.
- Account page: hide the whole login block once authenticated (not just the
  form), add an avatar Refresh button (cache-busted NMSR re-fetch), flatten the
  avatar (no bevel). New i18n key account.refresh.
- Register page: new REGISTRATION_SHOW_INVITE env (default false/hidden) toggles
  the invite-code field independently of the REGISTRATION_MODE backend gate.
- Members roster: drop the `admin` account, render full-body via a new
  ROSTER_AVATAR_MODE (default fullbodyiso); portrait tiles.
- Style: flatten emboss on feature icons (.picon) + player tiles (.roster-tile).
  PixelIcon gains optional image support (/icons/<name>.png|svg).
- Favicon now /favicon.png (committed) on all pages.
- Docs: plan/09-landing.md Assets section (logo/favicon/features-icons drop
  points) + default-language note; .env.example documents the two new vars.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

landing/src/styles/main.css

@@ -484,11 +484,11 @@ section { position: relative; z-index: 1; }
   gap: 8px;
   padding: 12px 8px;
   background: var(--bg-2);
-  box-shadow: inset 1px 1px 0 var(--bevel-lo), inset -1px -1px 0 var(--bevel-hi);
 }
 .roster-tile img {
-  width: 48px;
-  height: 48px;
+  width: auto;
+  height: 72px;
+  object-fit: contain;
   image-rendering: pixelated;
 }
 .roster-name {
@@ -522,7 +522,7 @@ section { position: relative; z-index: 1; }
 .feat h3 { font-size: 21px; margin-bottom: 8px; }
 .feat p { margin: 0; color: var(--muted); font-size: 16px; }
 
-/* pixel icon */
+/* pixel icon — plain (no bevel) */
 .picon {
   width: 52px; height: 52px; flex-shrink: 0;
   display: grid;
@@ -530,12 +530,17 @@ section { position: relative; z-index: 1; }
   grid-template-rows: repeat(7, 1fr);
   background: var(--slot);
   padding: 4px;
-  box-shadow: inset 2px 2px 0 var(--bevel-lo), inset -2px -2px 0 var(--bevel-hi);
   image-rendering: pixelated;
 }
 .picon i { background: transparent; }
 .picon i.on { background: var(--accent); }
 .picon i.go { background: var(--gold); }
+/* custom image icon (PixelIcon `img` prop) */
+.picon-img {
+  width: 52px; height: 52px; flex-shrink: 0;
+  object-fit: contain;
+  image-rendering: pixelated;
+}
 
 /* ============================================================
    HOW TO JOIN — steps