feat: add Discord channel, OpenCode runtime, rename to Regolith

- Discord channel integration (discord.js) with mention stripping, attachment tagging, reply context, message chunking
- OpenCode runtime with CLI and SDK modes, SQLite session persistence, idle timeout cleanup
- Multi-channel architecture: WhatsApp + Discord simultaneous or independent via DISCORD_ONLY/DISCORD_BOT_TOKEN
- Config additions: DISCORD_BOT_TOKEN, DISCORD_ONLY, OPENCODE_MODE, OPENCODE_MODEL, OPENCODE_TIMEOUT, OPENCODE_SESSION_TTL_HOURS
- Updated README and CLAUDE.md documentation
- Renamed project to Regolith in package.json

src/opencode/types.ts

@@ -0,0 +1,32 @@
+export type RuntimeMode = 'cli' | 'sdk';
+
+export interface OpenCodeConfig {
+  mode: RuntimeMode;
+  command: string;
+  serverUrl: string;
+  serverPassword?: string;
+  timeoutMs: number;
+  model?: string;
+  provider?: string;
+  systemPrompt?: string;
+  workspaceDir?: string;
+  format: 'json' | 'default';
+  sessionTtlHours: number;
+}
+
+export interface AgentResponse {
+  text: string;
+  sessionId?: string;
+  model?: string;
+  error?: string;
+  durationMs: number;
+  rateLimited: boolean;
+}
+
+export interface LiveSession {
+  conversationId: string;
+  sessionId?: string;
+  createdAt: number;
+  lastActive: number;
+  messageCount: number;
+}