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.

cmd/char-migrate/main.go

@@ -0,0 +1,90 @@
+// Command char-migrate mints a confirmed D&D character for one or more users,
+// for the "stuck adventurer" cases the boredom ticker can't reach: veteran
+// legacy players who never triggered auto-migration, and players who abandoned
+// !setup at race pick. It reuses the game's own constructors (stats, HP/AC,
+// resources, spells) via plugin.AdminBuildConfirmedCharacter.
+//
+// It opens the SAME gogobee.db the live bot uses (WAL + busy_timeout), so it is
+// safe to run alongside the running process — but snapshot the db dir first.
+//
+// Usage:
+//
+//	char-migrate -data /home/reala/gogobee/data \
+//	    '@nonk:parodia.dev:human:rogue:4' \
+//	    '@knightstar:matrix.org:half_elf:warlock:1'
+//
+// Each spec is mxid:race:class:level (mxid contains colons, so we split from
+// the right for the last three fields).
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+
+	"gogobee/internal/db"
+	"gogobee/internal/plugin"
+
+	"maunium.net/go/mautrix/id"
+)
+
+func main() {
+	dataDir := flag.String("data", "", "data dir containing gogobee.db (e.g. /home/reala/gogobee/data)")
+	flag.Parse()
+
+	if *dataDir == "" || flag.NArg() == 0 {
+		fmt.Fprintln(os.Stderr, "usage: char-migrate -data <dir> '<mxid>:<race>:<class>:<level>' ...")
+		os.Exit(2)
+	}
+
+	if err := db.Init(*dataDir); err != nil {
+		log.Fatalf("db init: %v", err)
+	}
+
+	for _, spec := range flag.Args() {
+		uid, race, class, level, err := parseSpec(spec)
+		if err != nil {
+			log.Fatalf("bad spec %q: %v", spec, err)
+		}
+		c, err := plugin.AdminBuildConfirmedCharacter(uid, race, class, level)
+		if err != nil {
+			log.Fatalf("build %s: %v", uid, err)
+		}
+		fmt.Printf("OK  %-28s %s %s L%d  HP=%d AC=%d  STR%d DEX%d CON%d INT%d WIS%d CHA%d\n",
+			uid, c.Race, c.Class, c.Level, c.HPMax, c.ArmorClass,
+			c.STR, c.DEX, c.CON, c.INT, c.WIS, c.CHA)
+	}
+}
+
+// parseSpec splits mxid:race:class:level. The mxid itself contains a colon
+// (@user:server), so split the last three fields off the right.
+func parseSpec(spec string) (id.UserID, plugin.DnDRace, plugin.DnDClass, int, error) {
+	i := strings.LastIndex(spec, ":")
+	if i < 0 {
+		return "", "", "", 0, fmt.Errorf("missing :level")
+	}
+	level, err := strconv.Atoi(spec[i+1:])
+	if err != nil {
+		return "", "", "", 0, fmt.Errorf("level: %w", err)
+	}
+	rest := spec[:i]
+	j := strings.LastIndex(rest, ":")
+	if j < 0 {
+		return "", "", "", 0, fmt.Errorf("missing :class")
+	}
+	class := rest[j+1:]
+	rest = rest[:j]
+	k := strings.LastIndex(rest, ":")
+	if k < 0 {
+		return "", "", "", 0, fmt.Errorf("missing :race")
+	}
+	race := rest[k+1:]
+	mxid := rest[:k]
+	if mxid == "" || race == "" || class == "" {
+		return "", "", "", 0, fmt.Errorf("empty field")
+	}
+	return id.UserID(mxid), plugin.DnDRace(race), plugin.DnDClass(class), level, nil
+}