Add space groups, fix HLTB scraper, fix quote wall E2EE, improve tarot prompts

Space groups: automatic room grouping via membership overlap percentage.
Rooms with sufficient shared members are grouped together so leaderboards,
trivia scores, and stats aggregate across the community. Uses strict
clique-based algorithm (every room must meet threshold with every other
room in group). Configurable via SPACE_GROUP_THRESHOLD env var. Persisted
to SQLite, recomputed hourly and on startup.

HLTB scraper: rewrote for new howlongtobeat.com API (two-step token auth
via /api/finder/init + /api/finder endpoint).

Quote wall: fix E2EE decrypt flow for reply-to-save (ParseRaw before
Decrypt, skip ParseRaw after Decrypt returns pre-parsed event). Fix
subcommand matching for delete/search. Remove broken star-reaction handler
and old quote handler from user.go.

Other fixes:
- Strip Matrix reply fallback before command detection (main.go)
- Increase Ollama context window to 8192
- Improve tarot spread prompts (~4x longer, narrative arc)
- Add "cards are props" instruction to tarot LLM prompt
- Fix movies.go CommandDef name mismatch
- Add Community category to !help
- Remove daily horoscope broadcast cron
- Update README with all changes

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

.env.example

@@ -38,6 +38,9 @@ FEATURE_TRIVIA=true  # set to "false" to disable trivia
 FEATURE_ESTEEMED=    # set to anything to enable satirical esteemed member posts
 ESTEEMED_ROOM=       # room ID for esteemed member posts (separate from broadcast rooms)
 
+# ---- Space Groups (automatic room grouping for community-wide leaderboards) ----
+SPACE_GROUP_THRESHOLD=50       # % of smaller room's members that must overlap (1-100, default 50)
+
 # ---- Missing Members (!haveyouseenthem / !missing) ----
 MISSING_THRESHOLD_DAYS=14     # days of inactivity before considered missing
 MISSING_MAX_DAYS=90           # days after which they're considered gone, not missing