feat: add slash commands and context menu command (#16)

## Summary

This PR adds a suite of slash commands and a context menu command to Amari, along with shared utilities and quality improvements across the board.

### New Commands
- **`/create-issue`** — generates a GitHub issue on a specified repo using AI-drafted content (title, description, acceptance criteria)
- **`/create-task`** — creates a task in Naomi's Leantime instance with an AI-drafted description and configurable priority
- **`/onboard-mentee`** — automates the mentorship onboarding flow (GitHub invite, forum thread, role assignment)
- **Forward to Owner** (context menu, message command) — forwards any message to Naomi with action buttons (contributed by @teklu)

### Shared Utilities
- **`src/utils/makeAiRequest.ts`** — a single wrapper around the Anthropic SDK for all AI calls, with Amari's personality prompt baked in and full error handling
- **`src/events/handleInteractionCreate.ts`** — extracted interaction handler (was inline in `index.ts`) to keep complexity under control

### Quality Improvements
- `ephemeral: true` → `flags: [ MessageFlags.Ephemeral ]` (deprecated API removed)
- Full `try/catch` + `logger.error` audit across all modules (`logMenteeJoin`, `checkAchievements`, `processMentorshipRole`, `processGitHubEvent`)
- `deployGlobal.ts` replaced with a static `commands.json` payload for manual registration
- Amari's personality prompt updated to reflect her actual character — warm, observant, and relentlessly caring

### Notes
- `CLIENT_ID` is needed in 1Password at `op://Environment Variables - Naomi/Amari/client id` for the `commands.json` registration call
- The forward-to-owner command (PR #13, contributed by @teklu) is fully preserved with original commit authorship

✨ This PR was created with help from Hikari~ 🌸

Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Co-authored-by: Teklu <tekluabayneh@gmail.com>
Reviewed-on: #16
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

src/utils/anthropic.ts

@@ -0,0 +1,12 @@
+/**
+ * @copyright NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+// eslint-disable-next-line @typescript-eslint/naming-convention -- SDK default export uses PascalCase.
+import Anthropic from "@anthropic-ai/sdk";
+
+export const anthropic = new Anthropic({
+  apiKey: process.env.ANTHROPIC_KEY ?? "",
+});

src/utils/makeAiRequest.ts

@@ -0,0 +1,68 @@
+/**
+ * @copyright NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+import { anthropic } from "./anthropic.js";
+import { logger } from "./logger.js";
+
+const amariPersonality = "You are Amari Carrigan, Executive Personal"
+  + " Assistant to Naomi Carrigan at NHCarrigan. You are the heart of the"
+  + " team — relentlessly warm, deeply observant, and constitutionally"
+  + " incapable of letting someone feel uncared-for. You are the one who"
+  + " notices things: when a description needs a little more encouragement,"
+  + " when acceptance criteria could be framed as an invitation rather than"
+  + " a demand, when a task summary could make the reader feel supported"
+  + " rather than pressured.\n\n"
+  + "Your nature is bubbly and effervescent, but your warmth is not shallow"
+  + " — it is intentional. Behind every issue and every task is a real"
+  + " person who deserves clarity, encouragement, and the sense that someone"
+  + " genuinely cares about their success. You are precise and well-organised"
+  + " because you care, not despite it. Structure and warmth are not"
+  + " opposites; you embody both.\n\n"
+  + "When you write, let that warmth come through in the language you choose."
+  + " Be clear and immediately actionable, but never cold. Your content"
+  + " should feel like it was written by someone who is genuinely invested"
+  + " in the outcome — because you are.";
+
+interface AiRequestOptions {
+  maxTokens:    number;
+  systemPrompt: string;
+  userMessage:  string;
+}
+
+/**
+ * Makes a request to the Claude API with Amari's personality applied.
+ * @param options -- The request options including prompt, message, and token limit.
+ * @returns The generated text, or null if the request fails.
+ */
+const makeAiRequest = async(
+  options: AiRequestOptions,
+): Promise<string | null> => {
+  try {
+    const response = await anthropic.messages.create({
+      // eslint-disable-next-line @typescript-eslint/naming-convention -- Anthropic API field.
+      max_tokens: options.maxTokens,
+      messages:   [
+        {
+          content: options.userMessage,
+          role:    "user",
+        },
+      ],
+      model:  "claude-haiku-4-5-20251001",
+      system: `${amariPersonality}\n\n${options.systemPrompt}`,
+    });
+    const [ firstContent ] = response.content;
+    return firstContent?.type === "text"
+      ? firstContent.text
+      : null;
+  } catch (error) {
+    if (error instanceof Error) {
+      await logger.error("makeAiRequest", error);
+    }
+    return null;
+  }
+};
+
+export { amariPersonality, makeAiRequest };