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>

pyproject.toml

@@ -10,5 +10,8 @@ dependencies = []
 requires = ["hatchling"]
 build-backend = "hatchling.build"
 
+[dependency-groups]
+dev = ["pytest>=8.0"]
+
 [project.scripts]
 h2g2 = "h2g2.main:main"