feat: more automated announcements (#8)

### Explanation

Makes my life so much easier.

### Issue

_No response_

### Attestations

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

### Dependencies

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

### Style

- [x] I have run the linter and resolved any errors.
- [x] My pull request uses an appropriate title, matching the conventional commit standards.
- [x] 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

_No response_

### Versioning

Minor - My pull request introduces a new non-breaking feature.

Reviewed-on: #8
Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Co-committed-by: Naomi Carrigan <commits@nhcarrigan.com>

server/src/interfaces/announcementResponse.ts

@@ -0,0 +1,18 @@
+/**
+ * @copyright NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+/**
+ * This should match the JSON schema for the announcement response.
+ * @see {@link announcementJsonSchema}
+ */
+export interface AnnouncementResponse {
+  markdown: {
+    content: string;
+    title:   string;
+  };
+  plaintext: string;
+  threaded:  Array<string>;
+}

server/src/interfaces/announcementType.ts

@@ -0,0 +1,10 @@
+/**
+ * @copyright NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+/**
+ * This really only exists so we can do a type guard.
+ */
+export type AnnouncementType = "products" | "community" | "company";