feat: rename "App" templates to "Featured" and add admin TikTok slideshow import

[Copilot]

Renames the "App" section in Pack Templates to "Featured" across the UI. Adds an admin-only workflow to generate featured pack templates from TikTok packing slideshow content using GPT-4o and catalog vector search.

Featured Rename

• Translation keys updated: segmented control tab ("App" → "Featured"), badge label, form toggle label, and footnote
• No DB or logic changes — purely label/copy updates

TikTok Import — API (POST /api/pack-templates/generate-from-tiktok)

• Admin-only; returns 403 for non-admins
• Accepts tiktokUrl, imageUrls[] (extracted slideshow frames), optional caption, name, category, isAppTemplate
• Sends all images + caption to gpt-4o with a structured schema prompt to extract gear items (name, description, category, weight estimate, quantity, consumable, worn flags)
• Runs batch vector search against catalog for each detected item; prefers catalog match for name/weight/image, falls back to AI-detected values
• Inserts pack template + items in a single transaction; returns full template with items

// New schemas
GenerateFromTikTokRequestSchema  // tiktokUrl + imageUrls[] required
GenerateFromTikTokResponseSchema // PackTemplateWithItems

// Route registered at
packTemplatesRoutes.route('/', generateFromTikTokRoutes);

TikTok Import — Mobile UI (Admin only)

• New TikTokImportScreen: TikTok URL field, optional caption, dynamic list of slideshow image URL inputs (add/remove), generate button with loading state; on success navigates directly to the new template
• useGenerateTemplateFromTikTok mutation hook; syncs created template + items into Legend-State store on success
• TikTokImportIconButton shown in PackTemplateListScreen header only when user.role === 'ADMIN', navigates to /pack-templates/import-from-tiktok

Original prompt

We want to change the "App" section in Pack Templates to "Featured". We want to add the ability for admins to create a pack template from social media content. These are detailed packing list content and we want to use AI to automatically create pack template from them using the items in our catalog.
We want to start with tiktok slideshows for this phase. We extract and pass the images and other information to the AI (gpt4o). Instruct it to use the pack information and attachments provided and build the pack using the items in our catalog.

The user has attached the following file paths as relevant context:

• .github/copilot-instructions.md

Created from VS Code.

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