feat: drop the typed first-message hint from the Discord bridge (#741)

Owner decision. Typing the note into a brand-new non-Claude tab spent a model
turn per tab and, for a spawned worker or a scheduled run, landed with the first
real prompt. Claude keeps its hint through the system prompt, and every other CLI
is told nothing. The setting goes with the path it gated: sessionIdle, the fresh
set, isHintableSession and the session:idle wiring. sendInput loses `fromUser`,
which was only ever false for the hint, and the deps test pins that a reply is a
person's own input.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/types/discord.ts

@@ -37,11 +37,6 @@ export interface DiscordConfig {
   scope: WebhookScope;
   /** Tell each session how to reach the user (see DISCORD_STARTUP_HINT). On by default while the bridge is on. */
   startupHint: boolean;
-  /**
-   * Also type the hint, once, as the first message to a brand-new non-Claude CLI tab. Off by default: it spends a
-   * model turn per tab, and for a spawned worker or a cron session it lands on the same first idle as the real prompt.
-   */
-  typedHint: boolean;
 }
 
 export interface DiscordResult {