Wire game transitions end-to-end, add Guide lookup, add 79 tests

Transitions:
- Add I-HOUSEWRECK (tick 20) and I-VOGONS (tick 50) timed events to
  earth.py, queued at startup in main.py
- I-VOGONS demolishes Earth and moves player to Vogon Hold
- Fix airlock→Dark transition to call Dark room M-ENTER handler
- Fix dream-restore to support multiple callbacks (list instead of single)
- Add state.finish() call to RAMP for endgame victory

Guide system:
- Add 16-entry lookup database to GUIDE object (space, towel, vogons,
  poetry, beast, babel fish, earth, magrathea, marvin, etc.)
- "consult guide about X" now returns relevant entry text

Tests (79 passing):
- test_engine.py (14): containment, flags, articles, clock mechanics
- test_parser.py (20): directions, compound verbs, prepositions, synonyms
- test_earth.py (21): full opening sequence, puzzles, navigation
- test_vogon.py (4): room existence, Hold first-visit sequence
- test_dark.py (7): inventory clearing, dream dispatch, probabilities
- conftest.py: shared game fixture and send() helper

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/conftest.py

@@ -0,0 +1,75 @@
+import pytest
+from h2g2.engine.world import World
+from h2g2.engine.state import GameState
+from h2g2.engine.output import Output
+from h2g2.engine.clock import Clock
+from h2g2.engine.parser import Parser
+from h2g2.engine.loop import GameLoop
+from h2g2.content import globals_content, earth, vogon, heart, unearth, dark
+import h2g2.engine.verbs  # noqa: F401 — register handlers
+
+
+@pytest.fixture
+def game():
+    """Create a fully initialized game world."""
+    world = World()
+    globals_content.register(world)
+    earth.register(world)
+
+    output = Output()
+    clock = Clock()
+    state = GameState(world, output, clock)
+
+    state.protagonist = world.protagonist
+    state.here = world.get_room("BEDROOM")
+    state.winner = world.protagonist
+    state.lying_down = True
+
+    # Initialize flags (same as main.py)
+    state.flags["headache"] = True
+    state.flags["groggy"] = False
+    state.flags["groggy_counter"] = 0
+    state.flags["house_demolished"] = False
+    state.flags["earth_demolished"] = False
+    state.flags["in_front_of_bulldozer"] = False
+    state.flags["ford_arrived"] = False
+    state.flags["ford_has_satchel"] = True
+    state.flags["prosser_in_mud"] = False
+    state.flags["beer_counter"] = 0
+    state.flags["babel_fish_in_ear"] = False
+    state.flags["poem_enjoyed"] = False
+    state.flags["holding_no_tea"] = True
+    state.flags["dead_counter"] = 0
+    state.flags["vogon_prob"] = 100
+    state.flags["heart_prob"] = 0
+    state.flags["traal_prob"] = 60
+    state.flags["fleet_prob"] = 0
+    state.flags["whale_prob"] = 0
+
+    state.inventory_extras.append(
+        lambda s: "a splitting headache" if s.flags.get("headache") else None
+    )
+    state.inventory_extras.append(
+        lambda s: "no tea" if s.flags.get("holding_no_tea") else None
+    )
+
+    # Register content that needs state
+    vogon.register(world, state)
+    heart.register(world, state)
+    unearth.register(world, state)
+    dark.register(world, state)
+
+    parser = Parser()
+    loop = GameLoop(state, parser)
+
+    return state, parser, loop
+
+
+def send(game_tuple, command: str) -> str:
+    """Send a command to the game and return the output text."""
+    state, parser, loop = game_tuple
+    result = parser.parse(command, state)
+    if result:
+        loop._execute(result)
+    text = state.output.flush()
+    return text