feat: add text adventure shell (PLAN.md 3.4)

Zork-style dungeon crawler set in an abandoned data center / medieval dungeon.
11 rooms, 6 items, 3 puzzles (dark room, locked door, maintenance panel),
standard text adventure parser with verb aliases and direction shortcuts.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/shell/adventure/adventure.go

@@ -0,0 +1,114 @@
+package adventure
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+	"time"
+
+	"git.t-juice.club/torjus/oubliette/internal/shell"
+)
+
+const sessionTimeout = 10 * time.Minute
+
+// AdventureShell implements a Zork-style text adventure set in a dungeon/data center.
+type AdventureShell struct{}
+
+// NewAdventureShell returns a new AdventureShell instance.
+func NewAdventureShell() *AdventureShell {
+	return &AdventureShell{}
+}
+
+func (a *AdventureShell) Name() string        { return "adventure" }
+func (a *AdventureShell) Description() string { return "Zork-style text adventure dungeon crawler" }
+
+func (a *AdventureShell) Handle(ctx context.Context, sess *shell.SessionContext, rw io.ReadWriteCloser) error {
+	ctx, cancel := context.WithTimeout(ctx, sessionTimeout)
+	defer cancel()
+
+	dungeonName := configString(sess.ShellConfig, "dungeon_name", "THE OUBLIETTE")
+	game := newGame()
+
+	// Print banner and initial room.
+	banner := strings.ReplaceAll(adventureBanner(dungeonName), "\n", "\r\n")
+	fmt.Fprint(rw, banner)
+
+	// Show starting room.
+	startDesc := game.describeRoom(game.rooms[game.currentRoom])
+	startDesc = strings.ReplaceAll(startDesc, "\n", "\r\n")
+	fmt.Fprintf(rw, "%s\r\n\r\n", startDesc)
+
+	for {
+		if _, err := fmt.Fprint(rw, "> "); err != nil {
+			return nil
+		}
+
+		line, err := shell.ReadLine(ctx, rw)
+		if errors.Is(err, io.EOF) {
+			fmt.Fprint(rw, "\r\n")
+			return nil
+		}
+		if err != nil {
+			return nil
+		}
+
+		trimmed := strings.TrimSpace(line)
+		if trimmed == "" {
+			continue
+		}
+
+		result := game.dispatch(trimmed)
+
+		var output string
+		if result.output != "" {
+			output = result.output
+			output = strings.ReplaceAll(output, "\r\n", "\n")
+			output = strings.ReplaceAll(output, "\n", "\r\n")
+			fmt.Fprintf(rw, "%s\r\n", output)
+		}
+
+		// Log command and output to store.
+		if sess.Store != nil {
+			if err := sess.Store.AppendSessionLog(ctx, sess.SessionID, trimmed, output); err != nil {
+				return fmt.Errorf("append session log: %w", err)
+			}
+		}
+
+		if result.exit {
+			return nil
+		}
+	}
+}
+
+func adventureBanner(dungeonName string) string {
+	return fmt.Sprintf(`
+  ___  _   _ ____  _     ___ _____ _____ _____
+ / _ \| | | | __ )| |   |_ _| ____|_   _|_   _| ___
+| | | | | | |  _ \| |    | ||  _|   | |   | |  / _ \
+| |_| | |_| | |_) | |___ | || |___  | |   | | |  __/
+ \___/ \___/|____/|_____|___|_____| |_|   |_|  \___|
+
+Welcome to %s.
+
+You wake up in the dark. The air is cold and hums with electricity.
+This is a place where things are put to be forgotten.
+
+Type 'help' for commands. Type 'look' to examine your surroundings.
+
+`, dungeonName)
+}
+
+// configString reads a string from the shell config map with a default.
+func configString(cfg map[string]any, key, defaultVal string) string {
+	if cfg == nil {
+		return defaultVal
+	}
+	if v, ok := cfg[key]; ok {
+		if s, ok := v.(string); ok && s != "" {
+			return s
+		}
+	}
+	return defaultVal
+}