feat(monetization): lock the cosmetic ladder (loyalty model) + free Original pack

Nails down the premium unlock system per the design pass:
- FREE `original` topdown pack (NEW): the game's bare tiles — floor/wall/door/
  torch/features only, no furniture, so the free tavern reads plain (the intended
  "reason to unlock"). Registered in assetPacks (RK.THEMES.original) as the free
  default topdown pack; plain ASCII stays free (accessibility).
- Loyalty ladder (lifetime credits PURCHASED, cumulative, NOT deducted → buying to
  play also unlocks cosmetics): Interior 1, skins 5, iso 10, +tilepack 20, +iso 40,
  3D 50. Each row is data (tilepack OR skin) → operator appends more at any rung.
  DEFAULT_CATALOG (entitlements.js) + migration 028 + MONETIZATION.md ladder table.
- Tests updated to the new thresholds (catalogEntitlements_ultra, directEntryCredit_ultra).

Note: this reprices roguelike-interior from free → 1cr, so once deployed the free
tavern becomes bare (by design). Deploy is bundled with the single-player render-kit
migration so the free-tier change lands with its payoff. Suite 61/432 green.

src/migrations/028_cosmetic_ladder.sql

@@ -0,0 +1,16 @@
+-- 028: lock the cosmetic ladder (loyalty model — unlock by lifetime credits purchased, cumulative).
+-- Adds the FREE `original` bare-tiles baseline and reprices the ladder: Interior 1, skins 5, iso 10,
+-- +tilepack 20, +iso 40, 3D 50. Mirrors DEFAULT_CATALOG in src/multiplayer/entitlements.js.
+-- Idempotent. See docs/MONETIZATION.md.
+INSERT INTO cosmetic_catalog (pack_id, label, kind, projection, tier, unlock_min_credits, grant_only, active, sort_order, metadata) VALUES
+    ('original',             'Original Tiles',                'render-pack', 'topdown', 0, NULL, false, true,  0,  '{}'::jsonb),
+    ('roguelike-interior',   'Kenney Roguelike Interior',     'render-pack', 'topdown', 1, 1,    false, true,  10, '{}'::jsonb),
+    ('generated-skins',      'Premium Character Skins',       'render-pack', 'topdown', 1, 5,    false, true,  15, '{}'::jsonb),
+    ('iso-dungeon',          'Kenney Isometric Dungeon',      'render-pack', 'iso',     2, 10,   false, true,  20, '{}'::jsonb),
+    ('roguelike-dungeon',    'Roguelike Dungeon (Tiles)',     'render-pack', 'topdown', 2, 20,   false, true,  25, '{}'::jsonb),
+    ('iso-medieval',         'Medieval Town (Isometric)',     'render-pack', 'iso',     3, 40,   false, true,  30, '{}'::jsonb),
+    ('kenney-3d-characters', 'Kenney Animated 3D Characters', 'render-pack', '3d',      3, 50,   false, true,  40, '{}'::jsonb)
+ON CONFLICT (pack_id) DO UPDATE
+   SET label = EXCLUDED.label, kind = EXCLUDED.kind, projection = EXCLUDED.projection, tier = EXCLUDED.tier,
+       unlock_min_credits = EXCLUDED.unlock_min_credits, grant_only = EXCLUDED.grant_only,
+       active = true, sort_order = EXCLUDED.sort_order;

src/multiplayer/entitlements.js

@@ -10,32 +10,47 @@ const Appearance = require('./appearance');
 //   unlockMinCredits — lifetime-spend threshold to unlock, or null (not credit-unlockable).
 //   grantOnly       — only obtainable via an explicit grant/purchase.
 //   premium         — derived convenience flag: true unless the pack is free (no gate at all).
+// Cosmetic ladder. Unlock by LIFETIME CREDITS PURCHASED (cumulative — spend more, unlock more; NOT
+// deducted, so buying credits to play also walks you up the ladder) OR by subscription tier. Each
+// row is just data — a tilepack OR a char-skin, at any credit rung — so the operator adds more of
+// either by appending a row (+ assets + registerPack for a client pack). See docs/MONETIZATION.md.
+//
+//   free  original tiles (bare — no furniture, the "ugly tavern") + plain ASCII (in renderModes)
+//   1     Roguelike Interior (first premium tilepack)
+//   5     Character skins
+//   10    Iso technique (first iso pack)      20  another tilepack
+//   40    second iso pack                     50  3D technique
 const DEFAULT_CATALOG = Object.freeze({
-    'roguelike-interior': Object.freeze({
-        id: 'roguelike-interior', label: 'Kenney Roguelike Interior', kind: 'render-pack',
+    // FREE pleb baseline — the game's original bare tiles. Furniture kinds fall back to floor, so
+    // the free tavern is pointedly plain (just floor + walls + players/monsters). By design: it's
+    // the reason to unlock the richer packs.
+    'original': Object.freeze({
+        id: 'original', label: 'Original Tiles', kind: 'render-pack',
         projection: 'topdown', tier: 0, unlockMinCredits: null, grantOnly: false, premium: false
     }),
-    // Graduated ladder — unlock by lifetime credit spend OR by subscription tier, whichever comes
-    // first: Fancy(skins) at 1 credit / supporter, Iso at 10 / premium, 3D at 25 / operator.
-    'generated-skins': Object.freeze({
-        id: 'generated-skins', label: 'Premium Generated Skins', kind: 'render-pack',
+    'roguelike-interior': Object.freeze({
+        id: 'roguelike-interior', label: 'Kenney Roguelike Interior', kind: 'render-pack',
         projection: 'topdown', tier: 1, unlockMinCredits: 1, grantOnly: false, premium: true
     }),
-    'roguelike-dungeon': Object.freeze({
-        id: 'roguelike-dungeon', label: 'Roguelike Dungeon (Tiles)', kind: 'render-pack',
-        projection: 'topdown', tier: 1, unlockMinCredits: 1, grantOnly: false, premium: true
+    'generated-skins': Object.freeze({
+        id: 'generated-skins', label: 'Premium Character Skins', kind: 'render-pack',
+        projection: 'topdown', tier: 1, unlockMinCredits: 5, grantOnly: false, premium: true
     }),
     'iso-dungeon': Object.freeze({
         id: 'iso-dungeon', label: 'Kenney Isometric Dungeon', kind: 'render-pack',
         projection: 'iso', tier: 2, unlockMinCredits: 10, grantOnly: false, premium: true
     }),
+    'roguelike-dungeon': Object.freeze({
+        id: 'roguelike-dungeon', label: 'Roguelike Dungeon (Tiles)', kind: 'render-pack',
+        projection: 'topdown', tier: 2, unlockMinCredits: 20, grantOnly: false, premium: true
+    }),
     'iso-medieval': Object.freeze({
         id: 'iso-medieval', label: 'Medieval Town (Isometric)', kind: 'render-pack',
-        projection: 'iso', tier: 2, unlockMinCredits: 15, grantOnly: false, premium: true
+        projection: 'iso', tier: 3, unlockMinCredits: 40, grantOnly: false, premium: true
     }),
     'kenney-3d-characters': Object.freeze({
         id: 'kenney-3d-characters', label: 'Kenney Animated 3D Characters', kind: 'render-pack',
-        projection: '3d', tier: 3, unlockMinCredits: 25, grantOnly: false, premium: true
+        projection: '3d', tier: 3, unlockMinCredits: 50, grantOnly: false, premium: true
     })
 });