In-App Documentation Pages No Longer Error; Cleaner Share-by-Email Loading

Reached QA. This release fixes the in-app Documentation (/docs) section that was intermittently returning a 500 error, and resolves a build-time warning around the rich-text editor used by the "Share via Email" dialog. Documentation pages now load reliably and refresh their content automatically every five minutes.

The Documentation pages were rendering a 500 error because the data-fetching code was being used in a way Next.js treats as invalid during static/server rendering, breaking the docs experience embedded in the dashboard. Separately, the rich-text editor (CKEditor) powering the "Share via Email" dialog was being loaded on the server, which produced duplicated-module errors in the build logs and added unnecessary risk to the mail detail pages.

• Users can open the in-app Documentation section (/docs, individual articles, and tag pages) without hitting the 500 error.
• Documentation content now updates on its own roughly every 5 minutes, so published edits appear without a redeploy.
• The "Share via Email" dialog on mail and batch-mail detail pages continues to work, with the heavy editor now loaded only when needed in the browser. Cleaner builds reduce the chance of editor-related regressions.

• Added a new server-only documentation.server.services.ts that fetches Strapi content with Next.js ISR caching (next.revalidate, 300s), avoiding the DYNAMIC_SERVER_USAGE condition that caused the /docs 500s.
• Re-pointed the docs landing, layout, article ([slug]), and tag pages to this server service and added export const revalidate = 300 to article and tag pages.
• Extracted all Strapi mapping/normalization and type-guard helpers into a shared documentation.mappers.ts (349 lines), and removed the duplicated copies from the existing documentation.services.ts so client and server services share one implementation (no behavior change to mapping).
• On mails/[id] and batches/mails/[id], switched ShareViaMailDialog to a dynamic, client-only import (ssr: false) so the CKEditor bundle is never evaluated in Node, eliminating duplicated-module build errors.

Low-to-moderate. The docs data layer was duplicated into a new server service rather than reused, so any mapping divergence would surface as wrong/missing docs content; mitigated because mapping logic is now centralized in one shared file. The ssr: false change means the share dialog renders only after client hydration; verify it still opens. ISR caching means content can be up to 5 minutes stale by design.

• Open /docs, a specific article (/docs/<slug>), and a tag page (/docs/tags/<slug>) and confirm no 500 error; verify breadcrumbs, navigation (prev/next), and sidebar render.
• Publish/edit a doc in the CMS and confirm the change appears within ~5 minutes without redeploy.
• On a mail detail page and a batch mail detail page, open "Share via Email" and confirm the editor loads and a share can be sent.
• Confirm build/server logs no longer show CKEditor duplicated-module errors.