feat(skills): add inference.sh skill (terminal-based, no custom tools) (#1686)

Add inference.sh as a built-in skill that uses the terminal tool to
run infsh CLI commands. No custom tools or tool registration — the
skill teaches the agent how to use the infsh binary via terminal.

Covers 150+ AI apps: image gen (FLUX, Reve, Seedream), video (Veo,
Wan, Seedance), LLMs, search (Tavily, Exa), 3D, avatars, and more.

Includes reference docs for authentication, app discovery, running
apps, and CLI command reference.

Based on PR #1021 by @okaris, reworked as a skill-only integration.

Co-authored-by: okaris <okaris@users.noreply.github.com>

skills/inference-sh/cli/references/app-discovery.md

@@ -0,0 +1,112 @@
+# Discovering Apps
+
+## List All Apps
+
+```bash
+infsh app list
+```
+
+## Pagination
+
+```bash
+infsh app list --page 2
+```
+
+## Filter by Category
+
+```bash
+infsh app list --category image
+infsh app list --category video
+infsh app list --category audio
+infsh app list --category text
+infsh app list --category other
+```
+
+## Search
+
+```bash
+infsh app search "flux"
+infsh app search "video generation"
+infsh app search "tts" -l
+infsh app search "image" --category image
+```
+
+Or use the flag form:
+
+```bash
+infsh app list --search "flux"
+infsh app list --search "video generation"
+infsh app list --search "tts"
+```
+
+## Featured Apps
+
+```bash
+infsh app list --featured
+```
+
+## Newest First
+
+```bash
+infsh app list --new
+```
+
+## Detailed View
+
+```bash
+infsh app list -l
+```
+
+Shows table with app name, category, description, and featured status.
+
+## Save to File
+
+```bash
+infsh app list --save apps.json
+```
+
+## Your Apps
+
+List apps you've deployed:
+
+```bash
+infsh app my
+infsh app my -l  # detailed
+```
+
+## Get App Details
+
+```bash
+infsh app get falai/flux-dev-lora
+infsh app get falai/flux-dev-lora --json
+```
+
+Shows full app info including input/output schema.
+
+## Popular Apps by Category
+
+### Image Generation
+- `falai/flux-dev-lora` - FLUX.2 Dev (high quality)
+- `falai/flux-2-klein-lora` - FLUX.2 Klein (fastest)
+- `infsh/sdxl` - Stable Diffusion XL
+- `google/gemini-3-pro-image-preview` - Gemini 3 Pro
+- `xai/grok-imagine-image` - Grok image generation
+
+### Video Generation
+- `google/veo-3-1-fast` - Veo 3.1 Fast
+- `google/veo-3` - Veo 3
+- `bytedance/seedance-1-5-pro` - Seedance 1.5 Pro
+- `infsh/ltx-video-2` - LTX Video 2 (with audio)
+- `bytedance/omnihuman-1-5` - OmniHuman avatar
+
+### Audio
+- `infsh/dia-tts` - Conversational TTS
+- `infsh/kokoro-tts` - Kokoro TTS
+- `infsh/fast-whisper-large-v3` - Fast transcription
+- `infsh/diffrythm` - Music generation
+
+## Documentation
+
+- [Browsing the Grid](https://inference.sh/docs/apps/browsing-grid) - Visual app browsing
+- [Apps Overview](https://inference.sh/docs/apps/overview) - Understanding apps
+- [Running Apps](https://inference.sh/docs/apps/running) - How to run apps