Add tutorial zones (flower and treehouse)

Implements the new player funnel with two tutorial zones:
- Flower: 7x7 sealed zone with translucent petals, spawn at center
- Treehouse: 20x15 platform zone with rope ladder and branch exits

Both zones are bounded (non-toroidal) and include portals for progression.

content/zones/flower.toml

@@ -0,0 +1,27 @@
+name = "flower"
+description = "you lie in the heart of a giant flower, warm light filtering through translucent petals"
+width = 7
+height = 7
+toroidal = false
+spawn_x = 3
+spawn_y = 3
+
+[terrain]
+rows = [
+    "ooooooo",
+    "ooo.ooo",
+    "oo...oo",
+    "o.....o",
+    "oo...oo",
+    "ooo.ooo",
+    "ooo.ooo",
+]
+
+[terrain.impassable]
+tiles = ["o"]
+
+[[portals]]
+x = 3
+y = 6
+target = "treehouse:10,7"
+label = "an opening in the petals"

content/zones/treehouse.toml

@@ -0,0 +1,41 @@
+name = "treehouse"
+description = "a sprawling treehouse platform high in an ancient oak, branches creaking in the wind"
+width = 20
+height = 15
+toroidal = false
+spawn_x = 10
+spawn_y = 7
+
+[terrain]
+rows = [
+    "~TTTTTTTTTTTTTTTTTT~",
+    "~TToooooooooooooTTT~",
+    "~TToo..........ooTT~",
+    "~TTo............oT~~",
+    "~TTo............oT~~",
+    "~TTo............oT~~",
+    "~TTo............oT~~",
+    "...o............oT~~",
+    "~TTo............oT~~",
+    "~TTo............oT~~",
+    "~TTo............oT~~",
+    "~TTo............oT~~",
+    "~TToo..........ooT~~",
+    "~TTToooooooooooTTT~~",
+    "~TTT...oooo...TTTT~~",
+]
+
+[terrain.impassable]
+tiles = ["o", "~"]
+
+[[portals]]
+x = 10
+y = 14
+target = "overworld:500,500"
+label = "a rope ladder dangles into the mist below"
+
+[[portals]]
+x = 0
+y = 7
+target = "hub:7,14"
+label = "a narrow branch leads to a distant platform"

tests/test_tutorial_zones.py

@@ -0,0 +1,125 @@
+"""Tests for tutorial zones (flower and treehouse)."""
+
+import pathlib
+
+from mudlib.zones import load_zone
+
+
+def test_load_flower_zone():
+    """Load the flower zone and verify basic properties."""
+    project_root = pathlib.Path(__file__).resolve().parents[1]
+    flower_path = project_root / "content" / "zones" / "flower.toml"
+
+    zone = load_zone(flower_path)
+
+    assert zone.name == "flower"
+    assert zone.width == 7
+    assert zone.height == 7
+    assert zone.toroidal is False
+    assert zone.spawn_x == 3
+    assert zone.spawn_y == 3
+    assert len(zone.terrain) == 7
+
+
+def test_flower_zone_mostly_sealed():
+    """Verify flower zone has mostly sealed borders with impassable petals."""
+    project_root = pathlib.Path(__file__).resolve().parents[1]
+    flower_path = project_root / "content" / "zones" / "flower.toml"
+
+    zone = load_zone(flower_path)
+
+    # Verify 'o' is impassable (petals)
+    assert "o" in zone.impassable
+
+    # Count impassable border tiles
+    border_tiles = []
+    # Top and bottom rows
+    for x in range(zone.width):
+        border_tiles.append((x, 0))
+        border_tiles.append((x, zone.height - 1))
+    # Left and right columns (excluding corners already counted)
+    for y in range(1, zone.height - 1):
+        border_tiles.append((0, y))
+        border_tiles.append((zone.width - 1, y))
+
+    impassable_border_count = sum(
+        1 for x, y in border_tiles if not zone.is_passable(x, y)
+    )
+
+    # Most of the border should be impassable (allow for 1-2 openings)
+    total_border = len(border_tiles)
+    assert impassable_border_count >= total_border - 2
+
+
+def test_flower_has_portal_to_treehouse():
+    """Verify flower zone has a portal targeting treehouse."""
+    project_root = pathlib.Path(__file__).resolve().parents[1]
+    flower_path = project_root / "content" / "zones" / "flower.toml"
+
+    zone = load_zone(flower_path)
+
+    # Find portals in zone contents
+    portals = [obj for obj in zone._contents if obj.__class__.__name__ == "Portal"]
+    assert len(portals) == 1
+
+    portal = portals[0]
+    assert portal.target_zone == "treehouse"
+    assert portal.target_x == 10
+    assert portal.target_y == 7
+    assert "petal" in portal.name.lower() or "opening" in portal.name.lower()
+
+
+def test_load_treehouse_zone():
+    """Load the treehouse zone and verify basic properties."""
+    project_root = pathlib.Path(__file__).resolve().parents[1]
+    treehouse_path = project_root / "content" / "zones" / "treehouse.toml"
+
+    zone = load_zone(treehouse_path)
+
+    assert zone.name == "treehouse"
+    assert zone.width == 20
+    assert zone.height == 15
+    assert zone.toroidal is False
+    assert zone.spawn_x == 10
+    assert zone.spawn_y == 7
+    assert len(zone.terrain) == 15
+
+
+def test_treehouse_has_portal_to_overworld():
+    """Verify treehouse has a portal to the overworld."""
+    project_root = pathlib.Path(__file__).resolve().parents[1]
+    treehouse_path = project_root / "content" / "zones" / "treehouse.toml"
+
+    zone = load_zone(treehouse_path)
+
+    # Find portals
+    portals = [obj for obj in zone._contents if obj.__class__.__name__ == "Portal"]
+
+    # Find the overworld portal
+    overworld_portals = [p for p in portals if p.target_zone == "overworld"]
+    assert len(overworld_portals) == 1
+
+    portal = overworld_portals[0]
+    assert portal.target_x == 500
+    assert portal.target_y == 500
+    assert "ladder" in portal.name.lower() or "mist" in portal.name.lower()
+
+
+def test_treehouse_has_portal_to_hub():
+    """Verify treehouse has a portal to the hub."""
+    project_root = pathlib.Path(__file__).resolve().parents[1]
+    treehouse_path = project_root / "content" / "zones" / "treehouse.toml"
+
+    zone = load_zone(treehouse_path)
+
+    # Find portals
+    portals = [obj for obj in zone._contents if obj.__class__.__name__ == "Portal"]
+
+    # Find the hub portal
+    hub_portals = [p for p in portals if p.target_zone == "hub"]
+    assert len(hub_portals) == 1
+
+    portal = hub_portals[0]
+    assert portal.target_x == 7
+    assert portal.target_y == 14
+    assert "branch" in portal.name.lower() or "platform" in portal.name.lower()