N5/D1a: journal pages — the Hollow King campaign collectible

First slice of the N5 story layer. Adds a 24-page serialized campaign
threaded through the zones as collectible journal pages.

- Storage: one journal_pages INTEGER bitmask on player_meta (bit i ==
  page i+1). DEFAULT 0 is correct for every existing row, so no bootstrap.
  Grants are an atomic bitwise-OR (INSERT ... ON CONFLICT DO UPDATE SET
  journal_pages = journal_pages | excluded.journal_pages) so a page found
  mid-expedition can't be lost to a stale character save. Journal pages
  are therefore grant-only + overlay-read, never in the bulk upsert.
- Drop seam: elite kills roll a page (22%, tunable) in dropZoneLoot,
  gated on isElite — bosses get epilogues (D1b), not pages. Not on
  SimulateCombat's path, so TestCombatCharacterization is byte-identical.
- Viewer: !adventure journal renders found pages in story order with runs
  of missing pages collapsed to a single "…".
- Catalog + bitmask helpers + render live in the new
  adventure_flavor_campaign.go; the pages are in-world found artifacts,
  not TwinBee's voice.

Golden byte-identical; go test ./... green (incl. a real-DB round-trip
that pins the atomic OR + overlay read).

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

internal/plugin/adventure_character.go

@@ -111,6 +111,10 @@ type AdventureCharacter struct {
 	CraftsSucceeded  int
 	DeathSource      string // "adventure" | "arena" | "" (legacy/unknown — treated as adventure)
 	DeathLocation    string // human-readable location of last death; cleared on revive is not required
+	// N5/D1 the Hollow King campaign. Bitmask of discovered journal pages (bit i
+	// == page i+1). Read-only overlay from player_meta.journal_pages; writes go
+	// through the atomic grantJournalPageDB, never the bulk character save.
+	JournalPages int64
 }
 
 type AdvEquipment struct {