Add modular app structure for L2 server

- Create app factory with routers and templates
- Auth, assets, activities, anchors, storage, users, renderers routers
- Federation router for WebFinger and nodeinfo
- Jinja2 templates for L2 pages
- Config and dependency injection

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/config.py

@@ -0,0 +1,56 @@
+"""
+L2 Server Configuration.
+
+Environment-based settings for the ActivityPub server.
+"""
+
+import os
+from dataclasses import dataclass
+from pathlib import Path
+
+
+@dataclass
+class Settings:
+    """L2 Server configuration."""
+
+    # Domain and URLs
+    domain: str = os.environ.get("ARTDAG_DOMAIN", "artdag.rose-ash.com")
+    l1_public_url: str = os.environ.get("L1_PUBLIC_URL", "https://celery-artdag.rose-ash.com")
+    effects_repo_url: str = os.environ.get("EFFECTS_REPO_URL", "https://git.rose-ash.com/art-dag/effects")
+    ipfs_gateway_url: str = os.environ.get("IPFS_GATEWAY_URL", "")
+
+    # L1 servers
+    l1_servers: list = None
+
+    # Cookie domain for cross-subdomain auth
+    cookie_domain: str = None
+
+    # Data directory
+    data_dir: Path = None
+
+    # JWT settings
+    jwt_secret: str = os.environ.get("JWT_SECRET", "")
+    jwt_algorithm: str = "HS256"
+    access_token_expire_minutes: int = 60 * 24 * 30  # 30 days
+
+    def __post_init__(self):
+        # Parse L1 servers
+        l1_str = os.environ.get("L1_SERVERS", "https://celery-artdag.rose-ash.com")
+        self.l1_servers = [s.strip() for s in l1_str.split(",") if s.strip()]
+
+        # Cookie domain
+        env_cookie = os.environ.get("COOKIE_DOMAIN")
+        if env_cookie:
+            self.cookie_domain = env_cookie
+        else:
+            parts = self.domain.split(".")
+            if len(parts) >= 2:
+                self.cookie_domain = "." + ".".join(parts[-2:])
+
+        # Data directory
+        self.data_dir = Path(os.environ.get("ARTDAG_DATA", str(Path.home() / ".artdag" / "l2")))
+        self.data_dir.mkdir(parents=True, exist_ok=True)
+        (self.data_dir / "assets").mkdir(exist_ok=True)
+
+
+settings = Settings()