N7/B2: Renown — prestige past the L20 cap

Overflow XP that grantDnDXP used to drop at L20 now accumulates as Renown
on player_meta.renown_xp (cumulative, atomic +=; renown_level derived as
renown_xp/25000). The reward is prestige-only: a derived rank ladder
(Renowned→…→Eternal), a cosmetic ✦N marker on the sheet and leaderboard,
a games-room shout on rank promotion, and !level progress once capped.

Renown perks are the two combat-neutral economy levers only — +loot / +XP,
capped at a streak-30 grant's economic half (+15% / +20%). combat_stats.go
reads DeathModifier/SuccessBonus/ExceptionalBonus (which map to Defense/
Attack/CritRate) but never LootQuality/XPMultiplier, so renown pays out even
through loadCombatBonuses without moving the golden or the balance corpus.
The plan's "-death penalty" perk is deliberately dropped (it would inflate
Defense).

The overflow→renown conversion and the character save commit in one
transaction (saveDnDCharacterExec now takes an executor), so a crash can
neither drop the overflow nor double-credit it on the next grant.

Schema: renown_xp column, DEFAULT 0 correct for every existing row, no
bootstrap (journal_pages/epilogue_cleared pattern).

Claude-Session: https://claude.ai/code/session_017mEwUmmS7aQTP2NQXj6rUa

internal/plugin/adventure.go

@@ -646,6 +646,7 @@ func (p *AdventurePlugin) handleMenu(ctx MessageContext) error {
 	treasures, _ := loadAdvTreasureBonuses(char.UserID)
 	buffs, _ := loadAdvActiveBuffs(char.UserID)
 	bonuses := computeAdvBonuses(treasures, buffs, char.CurrentStreak, false)
+	applyRenownBonuses(bonuses, char.RenownLevel()) // N7/B2 — activity path only, never combat
 	balance := p.euro.GetBalance(char.UserID)
 
 	text := renderAdvMorningDM(char.UserID, equip, balance, bonuses, holName)
@@ -796,6 +797,7 @@ func (p *AdventurePlugin) handleLeaderboard(ctx MessageContext) error {
 			ForagingSkill: c.ForagingSkill,
 			FishingSkill:  c.FishingSkill,
 			CurrentStreak: c.CurrentStreak,
+			Renown:        renownLevelForUser(c.UserID),
 		})
 	}
 	text := renderAdvLeaderboard(entries)