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>

internal/plugin/movies.go

@@ -110,7 +110,7 @@ func (p *MoviesPlugin) Commands() []CommandDef {
 		{Name: "movie watch", Description: "Add a movie to your watchlist", Usage: "!movie watch <title>", Category: "Entertainment"},
 		{Name: "movie watching", Description: "List your movie watchlist", Usage: "!movie watching", Category: "Entertainment"},
 		{Name: "movie unwatch", Description: "Remove from watchlist by TMDB ID", Usage: "!movie unwatch <id>", Category: "Entertainment"},
-		{Name: "upcoming movies", Description: "Show upcoming movies", Usage: "!upcoming movies", Category: "Entertainment"},
+		{Name: "upcoming", Description: "Show upcoming movies", Usage: "!upcoming movies", Category: "Entertainment"},
 	}
 }