adventure: mint a confirmed sheet for a stuck adventurer

The boredom ticker needs a confirmed dnd_character, so two populations
never leave on their own: veteran legacy players with an
adventure_characters row but no dnd_character (auto-migration only fires
on active play, which an idle player never does), and players who
abandoned !setup at race pick (pending_setup=1). Both are correct
guards in tryBoredomStart, not bugs — the fix is to hand them a finished
sheet.

AdminBuildConfirmedCharacter forces a race/class/level and reuses the
same constructors as auto-migration and !setup confirm (class-tuned
standard array, racial mods, HP/AC, resource pool, caster spells+slots),
with auto_migrated=1 so the player can freely !setup-rebuild the class
that was chosen for them. cmd/char-migrate is the one-off that drives it
against a live gogobee.db.

internal/plugin/admin_char_migrate.go

@@ -0,0 +1,73 @@
+package plugin
+
+import (
+	"fmt"
+	"log/slog"
+	"time"
+
+	"maunium.net/go/mautrix/id"
+)
+
+// AdminBuildConfirmedCharacter mints (or overwrites) a confirmed D&D character
+// for one user with an explicitly chosen race/class/level, reusing the same
+// constructors as auto-migration and !setup confirm: class-tuned standard
+// array + racial mods, the canonical HP/AC formulas, resource pool, and — for
+// casters — the starter spell list and slot pool.
+//
+// It exists for the "stuck adventurer" cases the boredom ticker can't reach on
+// its own:
+//
+//   - A veteran legacy player with an adventure_characters row but no
+//     dnd_character (never triggered auto-migration because auto-migration only
+//     fires on active play — an idle player never does). Pass the class/race the
+//     faithful migration would infer to reproduce it exactly.
+//   - A player who abandoned !setup at race pick (pending_setup=1, no class), so
+//     tryBoredomStart skips them forever. This overwrites the draft with a
+//     finished sheet.
+//
+// AutoMigrated is set so the player can freely rebuild via !setup (no respec
+// cooldown) when they return — the class was assigned for them, not chosen.
+//
+// SaveDnDCharacter upserts on user_id, so an existing pending draft is replaced.
+// initResources / ensureSpellsForCharacter are idempotent.
+func AdminBuildConfirmedCharacter(userID id.UserID, race DnDRace, class DnDClass, level int) (*DnDCharacter, error) {
+	if level < 1 {
+		level = 1
+	}
+	scores := applyRaceMods(race, classStatPriority(class))
+	c := &DnDCharacter{
+		UserID:       userID,
+		Race:         race,
+		Class:        class,
+		Level:        level,
+		STR:          scores[0], DEX: scores[1], CON: scores[2],
+		INT:          scores[3], WIS: scores[4], CHA: scores[5],
+		PendingSetup: false,
+		AutoMigrated: true,
+		CreatedAt:    time.Now().UTC(),
+		UpdatedAt:    time.Now().UTC(),
+	}
+	conMod := abilityModifier(c.CON)
+	dexMod := abilityModifier(c.DEX)
+	c.HPMax = computeMaxHP(c.Class, conMod, c.Level)
+	c.HPCurrent = c.HPMax
+	c.ArmorClass = computeAC(c.Class, dexMod)
+	c.ShortRestCharges = c.Level
+
+	if err := ensurePlayerMetaSeed(userID); err != nil {
+		return nil, fmt.Errorf("seed player_meta: %w", err)
+	}
+	if err := SaveDnDCharacter(c); err != nil {
+		return nil, fmt.Errorf("save dnd_character: %w", err)
+	}
+	if err := initResources(userID, c.Class); err != nil {
+		return nil, fmt.Errorf("init resources: %w", err)
+	}
+	if err := ensureSpellsForCharacter(c); err != nil {
+		return nil, fmt.Errorf("seed spells: %w", err)
+	}
+	slog.Info("admin: built confirmed character",
+		"user", userID, "race", race, "class", class, "level", level,
+		"hp", c.HPMax, "ac", c.ArmorClass)
+	return c, nil
+}