QUA-1756: Restructure anomaly docs and document Assignees

[RafaelOsiro]

Overview

Restructures the Anomalies section into Deep Dive and How-tos hubs and documents the new Assignees feature end-to-end.

Key Changes

• anomalies/deep-dive/: new hub grouping Insights, Source Record, Types, Status, Fingerprints, and the new Assignees deep-dive.
• anomalies/how-tos/: replaces Manage Anomalies; adds Edit Description and Edit Tags (split from Edit Anomalies) plus the new Assignee subgroup (Add, Remove, Bulk-Assign).
• anomalies/api.md: new Anomalies API reference with a dedicated Manage assignees subsection.
• anomalies/faq.md: new Anomalies FAQ covering General, Types, Status, Fingerprints, Tags, Comments, Source Records, Assignees, Permissions, Filtering, and Bulk Operations.
• explore/anomalies.md: documents the new Assigned subtab and Assignees filter.
• in-app-notifications.md: adds the Assignment notification type alongside Flow and Mention.
• mkdocs.yml: nav restructured to match the new hubs and redirects added for every legacy path.

Pages to Test

• http://localhost:8000/anomalies/overview/ — Types link points at deep-dive/types.md.
• http://localhost:8000/anomalies/deep-dive/assignees/ — H1 "Anomaly Assignees"; sections cover the field, inheritance, permissions, notifications, history, the three-concept comparison table (Owner / Default Anomaly Assignee / Assignees), and filtering.
• http://localhost:8000/anomalies/how-tos/assignee/add-assignee/ — H1 carries the brick :material-plus-circle: icon; two tabs (Anomaly Overview / Anomaly Explore) with identical 6-step flow; single info admonition at the end covers permissions + notification rule.
• http://localhost:8000/anomalies/how-tos/assignee/remove-assignee/ — H1 carries the brick :material-minus-circle: icon; X-button references are labeled Remove (not "X"); note callout about self-unassignment plus tip cross-link to Bulk-Assign.
• http://localhost:8000/anomalies/how-tos/assignee/bulk-assign/ — H1 carries the brick :material-dots-vertical-circle: icon; ellipsis button labeled Bulk menu; Step 6 mentions the in-modal overwrite alert; closing warning flags the replace semantics.
• http://localhost:8000/anomalies/how-tos/filter-and-sort/ — Filter table row 8 documents the Assignees filter; the Filter by Assignee / Assigned subtab sections are wrapped in an HTML comment as a TODO.
• http://localhost:8000/anomalies/api/ — H1 with brick :material-api:; API docs tip banner immediately after the intro; PUT/PATCH require Author (Editor only for description); dedicated Manage assignees subsection under Update.
• http://localhost:8000/anomalies/faq/ — H1 with brick :material-help-circle-outline:; "Can an Acknowledged anomaly go back to Active?" answers Yes; permissions answer reflects Author-base + Editor-for-description.
• http://localhost:8000/explore/anomalies/ — Assigned subtab present between Acknowledged and All (screenshot pending, marked with TODO comment); filter table row 6 documents the Assignees filter.
• http://localhost:8000/using-the-platform/web-app/top-right-menu/in-app-notifications/ — Notification Types section with Flow / Assignment / Mention subsections; cross-link to the Deep Dive · Anomaly Assignees page.
• Legacy redirects still resolve: /anomalies/status/, /anomalies/types/, /anomalies/fingerprints/, /anomalies/details/insights/, /anomalies/details/source-record/, and /anomalies/manage-anomalies/<page>/ should all land on their new deep-dive/ or how-tos/ URLs.