Feature: /gif slash command with GIF picker (provider TBD)

[mjkatgithub]

Planning

• Milestone: Backlog (unassigned)
• Priority: P2
• Size: L
• Estimate: 5 SP

Goal

GIF search slash command with Discord-style picker: user types
/gif <query> (alias /giphy optional if provider allows), browses
results, sends selected GIF as m.image.

Background — provider & naming

• Discord exposes /gif and /tenor (both search animated GIFs on the web).
• Historical /giphy branding may not be available for commercial/client use;
  verify Giphy/Tenor/Klipy Terms of Service before integration (API key,
  attribution, caching, NSFW policy).
• Spike deliverable: short note in issue/PR on chosen provider + legal constraints.

Scope

Spike (required before implementation)

• Compare Giphy vs Tenor vs Klipy API: pricing, attribution, Matrix client
  precedent, NSFW filtering options.
• Document decision + env var for API key (NUXT_PUBLIC_* or server proxy).

Implementation

• /gif command on framework (Feature: Slash-command framework in composer #110) with <query> arg
• Horizontal GIF picker overlay (Discord reference UX)
• Debounced search API calls; loading/error states
• Send as m.image (GIF mimetype); reuse existing image send path
• Optional: /tenor alias pointing to same backend if we use Tenor
• i18n EN/DE

Out of scope (v1)

• GIF favorites / recent searches persistence
• Inline GIF without picker (auto-send first result)

Branch

feature/slash-command-gif-picker

Acceptance Criteria

• /gif cats opens picker with relevant results; click sends GIF to room.
• Provider ToS documented; attribution shown if required.
• Errors (no API key, rate limit, empty results) surfaced in UI.
• Works in threads.

Test Checklist

• Unit: search client mock, picker selection → send payload.
• Manual: compare UX to Discord screenshots; verify Element/Cinny display.

Blocked by

• Feature: Slash-command framework in composer #110 — slash-command framework

Epic

Sub-issue of #109.