feat: add automatic greeting upon connection (#42)

### Explanation

_No response_

### Issue

Closes #23

### Attestations

- [ ] I have read and agree to the [Code of Conduct](https://docs.nhcarrigan.com/community/coc/)
- [ ] I have read and agree to the [Community Guidelines](https://docs.nhcarrigan.com/community/guide/).
- [ ] My contribution complies with the [Contributor Covenant](https://docs.nhcarrigan.com/dev/covenant/).

### Dependencies

- [ ] I have pinned the dependencies to a specific patch version.

### Style

- [ ] I have run the linter and resolved any errors.
- [ ] My pull request uses an appropriate title, matching the conventional commit standards.
- [ ] My scope of feat/fix/chore/etc. correctly matches the nature of changes in my pull request.

### Tests

- [ ] My contribution adds new code, and I have added tests to cover it.
- [ ] My contribution modifies existing code, and I have updated the tests to reflect these changes.
- [ ] All new and existing tests pass locally with my changes.
- [ ] Code coverage remains at or above the configured threshold.

### Documentation

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### Versioning

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Reviewed-on: #42
Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Co-committed-by: Naomi Carrigan <commits@nhcarrigan.com>

src/lib/components/ConfigSidebar.svelte

@@ -9,6 +9,8 @@
     mcp_servers_json: null,
     auto_granted_tools: [],
     theme: "dark",
+    greeting_enabled: true,
+    greeting_custom_prompt: null,
   });
 
   let isOpen = $state(false);
@@ -220,6 +222,44 @@
       </div>
     </section>
 
+    <!-- Greeting Section -->
+    <section class="mb-6">
+      <h3 class="text-sm font-medium text-[var(--accent-primary)] uppercase tracking-wider mb-3">
+        Greeting
+      </h3>
+
+      <!-- Enable/Disable Toggle -->
+      <div class="mb-4">
+        <label class="flex items-center gap-3 cursor-pointer">
+          <input
+            type="checkbox"
+            bind:checked={config.greeting_enabled}
+            class="w-4 h-4 rounded border-[var(--border-color)] bg-[var(--bg-primary)] text-[var(--accent-primary)] focus:ring-[var(--accent-primary)]"
+          />
+          <span class="text-sm text-gray-300">Send greeting on connect</span>
+        </label>
+        <p class="text-xs text-gray-500 mt-1 ml-7">
+          Automatically greet you when a session starts with time-based messages
+        </p>
+      </div>
+
+      <!-- Custom Greeting Prompt -->
+      {#if config.greeting_enabled}
+        <div class="mb-4">
+          <label for="greeting-prompt" class="block text-sm text-gray-400 mb-1">
+            Custom Greeting Prompt <span class="text-gray-600">(optional)</span>
+          </label>
+          <textarea
+            id="greeting-prompt"
+            bind:value={config.greeting_custom_prompt}
+            rows="3"
+            placeholder="Leave empty for time-based greetings, or customize how you'd like to be greeted..."
+            class="w-full px-3 py-2 bg-[var(--bg-primary)] border border-[var(--border-color)] rounded-lg text-[var(--text-primary)] focus:outline-none focus:border-[var(--accent-primary)] resize-none"
+          ></textarea>
+        </div>
+      {/if}
+    </section>
+
     <!-- MCP Servers Section -->
     <section class="mb-6">
       <h3 class="text-sm font-medium text-[var(--accent-primary)] uppercase tracking-wider mb-3">