feedback: smoother markdown support (fixes #10340)

[RyanS4]

Fixes #10340

Problem

When learners, teachers, or administrators submit feedback, the dialog only provides a plain <textarea> input. Users cannot format their descriptions with lists, headings, or code, nor can they attach screenshots or images of UI bugs, content inaccuracies, or errors. Additionally, the feedback details/moderator view renders messages using raw text interpolation ({{message.message}}), meaning any Markdown or image links appear as raw text rather than formatted elements.

Proposed Solution

1. Submission Modal: Upgraded dialogFieldOptions in FeedbackDirective from 'type': 'textarea' to 'type': 'markdown' with imageGroup: 'community'. This activates Planet's native markdown editor toolbar with the Add Image action (DialogsImagesComponent).
2. Payload Normalization: Safely normalized post.message in FeedbackDirective.addFeedback() to handle both string and object { text: string, images: any[] } payloads from PlanetMarkdownTextboxComponent.
3. Moderator / Chat Viewer: Replaced raw string interpolation in FeedbackViewComponent with <planet-markdown [content]="message.message"></planet-markdown>, allowing screenshots, lists, bold text, code, and links to render cleanly.
4. Chat Bubble Framing: Added rounded card bubble styling (border, border-radius, and max-width: 90% with responsive img { max-width: 100% }) in feedback-view.scss so wide screenshots, charts, and multiline lists remain clearly framed inside distinct message bubbles.
5. Unit Tests: Added test coverage in feedback.directive.spec.ts for payload normalization and CouchDB persistence.

Justification & Practical Impact

• Greatly enhances the fidelity and clarity of bug reports and feature suggestions.
• Reduces moderator investigation overhead by enabling users to attach visual proof directly to their feedback tickets.
• Fully reuses Planet's existing Markdown and image upload pipeline without introducing any new third-party dependencies.