Fix: Detail Page Default Tab Rendering

[CynicalAtropos]

Description

Fixes detail page tab rendering when the route tab is missing or set to default.

The shared detail tab hook now resolves a render-safe activeTabKey before rendering Tabs, treating missing tab values and the internal default sentinel as the populated default tab. Performer, group, studio, and tag detail pages now use that resolved key for tab activation and panel queries.

This removes the per-page workaround that hid tabs until the URL effect ran, and also covers group detail pages and /default URLs.

Related Issue

Fixes #6798
Supercedes #6923
Also resolves the "Performer galleries not shown if performer has no scenes" bug in the bug tracker project board I believe

Testing

• pnpm.cmd run check
• pnpm.cmd run lint:js
• pnpm.cmd exec biome lint src/components/Shared/DetailsPage/Tabs.tsx src/components/Performers/PerformerDetails/Performer.tsx src/components/Groups/GroupDetails/Group.tsx src/components/Studios/StudioDetails/Studio.tsx src/components/Tags/TagDetails/Tag.tsx
• pnpm.cmd exec biome format src/components/Shared/DetailsPage/Tabs.tsx src/components/Performers/PerformerDetails/Performer.tsx src/components/Groups/GroupDetails/Group.tsx src/components/Studios/StudioDetails/Studio.tsx src/components/Tags/TagDetails/Tag.tsx
• git diff --check
• Manually confirmed with /[type]/[id], /[type]/[id]/default, and /[type]/[id]/test for performers, groups, studios, and tags for both when the first tab was populated and when the default tab populated was not the first.

Screenshots

N/A

Checklist

• I have read and understood the Contributing document.
• I have read and understood the AI Usage Policy document.
• [] I have made corresponding changes to the documentation (if applicable).

AI Usage Disclosure

• I have used AI tools to assist with this pull request, and I have disclosed the tools and how I used them below.

Used Codex to investigate the tab routing issue, draft the shared activeTabKey handling, and then manually reviewed and tested the changes.

Additional Context

The default tab value is accepted by several detail routes but does not correspond to a rendered Tab. Resolving it before render prevents React-Bootstrap from receiving an undefined or non-rendered active key, while the URL is still canonicalized afterward with history.replace.