feat(skills): gate 7 Linux/macOS-only skills from Windows via platforms frontmatter

Hermes's skill loader (agent/skill_utils.skill_matches_platform) already honors
the 'platforms:' frontmatter field and skip-loads skills whose declared
platform list doesn't include sys.platform. Seven bundled skills are in fact
Linux/macOS-only but never declared it, so they leak into Windows skill
listings and sometimes load with broken instructions.

Audited all 160 SKILL.md files (skills/ + optional-skills/) for Windows-
hostile signals: apt-get/brew/systemd/chmod+x install flows, ptrace/proc
runtime dependencies, bash-only launcher scripts, and package dependencies
with no Windows build. The 7 below fail one or more of those tests in a way
that fundamentally can't be papered over by docs edits:

  minecraft-modpack-server      bash start.sh + chmod +x + apt openjdk
  evaluating-llms-harness       lm-eval-harness bash launcher scripts
  distributed-llm-pretraining-
  torchtitan                    bash multi-node torchrun launcher
  python-debugpy                remote attach relies on /proc ptrace_scope
  pytorch-fsdp                  NCCL backend; Windows path is WSL only
  tensorrt-llm                  NVIDIA TensorRT-LLM has no Windows build
  searxng-search                Docker volume flow assumes POSIX $(pwd)

All seven get 'platforms: [linux, macos]'. On Windows the loader now skips
them silently — no more phantom skill listings, no more mid-task failures
because an Apple-only path was surfaced as a suggestion.

Cross-platform skills that merely CONTAIN signals in examples or
install-instructions (brew install as one of several paths, /tmp/ in a code
snippet, etc.) are NOT touched by this commit. A broader audit that
declares the ~140 cross-platform skills as 'platforms: [linux, macos,
windows]' can follow as a separate change once each has been verified
working on Windows.

The installed user copies under ~/AppData/Local/hermes/skills/ (when they
exist) are also patched so the running session reflects the gating
immediately, but only the in-repo files are committed here.

optional-skills/mlops/pytorch-fsdp/SKILL.md

@@ -5,6 +5,7 @@ version: 1.0.0
 author: Orchestra Research
 license: MIT
 dependencies: [torch>=2.0, transformers]
+platforms: [linux, macos]
 metadata:
   hermes:
     tags: [Distributed Training, PyTorch, FSDP, Data Parallel, Sharding, Mixed Precision, CPU Offloading, FSDP2, Large-Scale Training]

optional-skills/mlops/tensorrt-llm/SKILL.md

@@ -5,6 +5,7 @@ version: 1.0.0
 author: Orchestra Research
 license: MIT
 dependencies: [tensorrt-llm, torch]
+platforms: [linux, macos]
 metadata:
   hermes:
     tags: [Inference Serving, TensorRT-LLM, NVIDIA, Inference Optimization, High Throughput, Low Latency, Production, FP8, INT4, In-Flight Batching, Multi-GPU]

optional-skills/mlops/torchtitan/SKILL.md

@@ -5,6 +5,7 @@ version: 1.0.0
 author: Orchestra Research
 license: MIT
 dependencies: [torch>=2.6.0, torchtitan>=0.2.0, torchao>=0.5.0]
+platforms: [linux, macos]
 metadata:
   hermes:
     tags: [Model Architecture, Distributed Training, TorchTitan, FSDP2, Tensor Parallel, Pipeline Parallel, Context Parallel, Float8, Llama, Pretraining]

optional-skills/research/searxng-search/SKILL.md

@@ -4,6 +4,7 @@ description: Free meta-search via SearXNG — aggregates results from 70+ search
 version: 1.0.0
 author: hermes-agent
 license: MIT
+platforms: [linux, macos]
 metadata:
   hermes:
     tags: [search, searxng, meta-search, self-hosted, free, fallback]

skills/gaming/minecraft-modpack-server/SKILL.md

@@ -2,6 +2,7 @@
 name: minecraft-modpack-server
 description: "Host modded Minecraft servers (CurseForge, Modrinth)."
 tags: [minecraft, gaming, server, neoforge, forge, modpack]
+platforms: [linux, macos]
 ---
 
 # Minecraft Modpack Server Setup

skills/mlops/evaluation/lm-evaluation-harness/SKILL.md

@@ -5,6 +5,7 @@ version: 1.0.0
 author: Orchestra Research
 license: MIT
 dependencies: [lm-eval, transformers, vllm]
+platforms: [linux, macos]
 metadata:
   hermes:
     tags: [Evaluation, LM Evaluation Harness, Benchmarking, MMLU, HumanEval, GSM8K, EleutherAI, Model Quality, Academic Benchmarks, Industry Standard]

skills/software-development/python-debugpy/SKILL.md

@@ -4,6 +4,7 @@ description: "Debug Python: pdb REPL + debugpy remote (DAP)."
 version: 1.0.0
 author: Hermes Agent
 license: MIT
+platforms: [linux, macos]
 metadata:
   hermes:
     tags: [debugging, python, pdb, debugpy, breakpoints, dap, post-mortem]