feat: add inference.sh integration (infsh tool + skill) (#1682)

Add inference.sh CLI (infsh) as a tool integration, giving agents
access to 150+ AI apps through a single CLI — image gen (FLUX, Reve,
Seedream), video (Veo, Wan, Seedance), LLMs, search (Tavily, Exa),
3D, avatar/lipsync, and more. One API key manages all services.

Tools:
- infsh: run any infsh CLI command (app list, app run, etc.)
- infsh_install: install the CLI if not present

Registered as an 'inference' toolset (opt-in, not in core tools).
Includes comprehensive skill docs with examples for all app categories.

Changes from original PR:
- NOT added to _HERMES_CORE_TOOLS (available via --toolsets inference)
- Added 12 tests covering tool registration, command execution,
  error handling, timeout, JSON parsing, and install flow

Inspired by PR #1021 by @okaris.

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

skills/inference-sh/DESCRIPTION.md

@@ -0,0 +1,23 @@
+# inference.sh
+
+Run 150+ AI applications in the cloud via the [inference.sh](https://inference.sh) platform.
+
+**One API key for everything** - Access all AI services with a single account. No need to manage separate API keys for FLUX, Veo, Claude, Tavily, Twitter, etc. You can also bring your own keys if you prefer.
+
+## Available Skills
+
+- **cli**: The inference.sh CLI (`infsh`) for running AI apps
+
+## What's Included
+
+- **Image Generation**: FLUX, Reve, Seedream, Grok Imagine, Gemini
+- **Video Generation**: Veo, Wan, Seedance, OmniHuman, HunyuanVideo
+- **LLMs**: Claude, Gemini, Kimi, GLM-4 (via OpenRouter)
+- **Search**: Tavily, Exa
+- **3D**: Rodin
+- **Social**: Twitter/X automation
+- **Audio**: TTS, voice cloning
+
+## Tools
+
+This category provides the `infsh` and `infsh_install` tools in the `inference` toolset.