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>

toolsets.py

@@ -183,6 +183,12 @@ TOOLSETS = {
         "tools": ["execute_code"],
         "includes": []
     },
+
+    "inference": {
+        "description": "inference.sh CLI (infsh) — run 150+ AI apps: image gen (FLUX, Reve), video (Veo, Wan), LLMs, search (Tavily, Exa), 3D, and more",
+        "tools": ["infsh", "infsh_install"],
+        "includes": []
+    },
     
     "delegation": {
         "description": "Spawn subagents with isolated context for complex subtasks",