feat: add /drama-leaderboard command with historical composite scoring

Queries Messages, AnalysisResults, and Actions tables to rank users by a
composite drama score (weighted avg toxicity, peak toxicity, and action rate).
Public command with configurable time period (7d/30d/90d/all-time).

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

docs/plans/2026-02-27-drama-leaderboard-design.md

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+# Drama Leaderboard Design
+
+## Overview
+
+Public `/drama-leaderboard` slash command that ranks server members by historical drama levels using a composite score derived from DB data. Configurable time period (7d, 30d, 90d, all-time; default 30d).
+
+## Data Sources
+
+All from existing tables — no schema changes needed:
+
+- **Messages + AnalysisResults** (JOIN on MessageId): per-user avg/peak toxicity, message count
+- **Actions**: warning, mute, topic_remind, topic_nudge counts per user
+
+## Composite Score Formula
+
+```
+score = (avg_toxicity * 0.4) + (peak_toxicity * 0.2) + (action_rate * 0.4)
+```
+
+Where `action_rate = min(1.0, (warnings + mutes*2 + off_topic*0.5) / messages_analyzed * 10)`
+
+Normalizes actions relative to message volume so low-volume high-drama users rank appropriately.
+
+## Embed Format
+
+Top 10 users, ranked by composite score:
+
+```
+🥇 0.47 — Username
+   Avg: 0.32 | Peak: 0.81 | ⚠️ 3 | 🔇 1 | 📢 5
+```
+
+## Files to Modify
+
+- `utils/database.py` — add `get_drama_leaderboard(guild_id, days)` query method
+- `cogs/commands.py` — add `/drama-leaderboard` slash command with `period` choice parameter
+
+## Implementation Plan
+
+### Step 1: Database query method
+
+Add `get_drama_leaderboard(guild_id, days=None)` to `Database`:
+- Single SQL query joining Messages, AnalysisResults, Actions
+- Returns list of dicts with: user_id, username, avg_toxicity, max_toxicity, warnings, mutes, off_topic, messages_analyzed
+- `days=None` means all-time (no date filter)
+- Filter by GuildId to scope to the server
+
+### Step 2: Slash command
+
+Add `/drama-leaderboard` to `CommandsCog`:
+- Public command (no admin restriction)
+- `period` parameter with choices: 7d, 30d, 90d, all-time
+- Defer response (DB query may take a moment)
+- Compute composite score in Python from query results
+- Sort by composite score descending, take top 10
+- Build embed with ranked list and per-user stat breakdown
+- Handle empty results gracefully