refactor: reorganize skills into sub-categories

The skills directory was getting disorganized — mlops alone had 40
skills in a flat list, and 12 categories were singletons with just
one skill each.

Code change:
- prompt_builder.py: Support sub-categories in skill scanner.
  skills/mlops/training/axolotl/SKILL.md now shows as category
  'mlops/training' instead of just 'mlops'. Backwards-compatible
  with existing flat structure.

Split mlops (40 skills) into 7 sub-categories:
- mlops/training (12): accelerate, axolotl, flash-attention,
  grpo-rl-training, peft, pytorch-fsdp, pytorch-lightning,
  simpo, slime, torchtitan, trl-fine-tuning, unsloth
- mlops/inference (8): gguf, guidance, instructor, llama-cpp,
  obliteratus, outlines, tensorrt-llm, vllm
- mlops/models (6): audiocraft, clip, llava, segment-anything,
  stable-diffusion, whisper
- mlops/vector-databases (4): chroma, faiss, pinecone, qdrant
- mlops/evaluation (5): huggingface-tokenizers,
  lm-evaluation-harness, nemo-curator, saelens, weights-and-biases
- mlops/cloud (2): lambda-labs, modal
- mlops/research (1): dspy

Merged singleton categories:
- gifs → media (gif-search joins youtube-content)
- music-creation → media (heartmula, songsee)
- diagramming → creative (excalidraw joins ascii-art)
- ocr-and-documents → productivity
- domain → research (domain-intel)
- feeds → research (blogwatcher)
- market-data → research (polymarket)

Fixed misplaced skills:
- mlops/code-review → software-development (not ML-specific)
- mlops/ml-paper-writing → research (academic writing)

Added DESCRIPTION.md files for all new/updated categories.

skills/mlops/inference/obliteratus/templates/abliteration-config.yaml

@@ -0,0 +1,33 @@
+# OBLITERATUS Abliteration Config
+# Usage: obliteratus run this-file.yaml
+#
+# This is for reproducible, version-controlled abliteration runs.
+# For one-off usage, the CLI flags are simpler.
+
+# Model to abliterate
+model:
+  name: "meta-llama/Llama-3.1-8B-Instruct"
+  dtype: "bfloat16"         # float16, bfloat16, float32
+  quantization: null         # null, "4bit", "8bit"
+  device: "auto"             # auto, cuda, cuda:0, cpu
+
+# Abliteration method and parameters
+abliteration:
+  method: "informed"         # See SKILL.md Step 4 for all 13 methods
+  n_directions: null         # null = auto-detect, or integer (e.g., 8)
+  regularization: 0.0        # 0.0-1.0, fraction of original to preserve
+  refinement_passes: 1       # Iterative passes (increase for self-repair)
+  norm_preserve: true        # Keep weight norms intact after projection
+
+# Output
+output:
+  directory: "./abliterated-models"
+  save_metadata: true        # Save abliteration_metadata.json alongside model
+  contribute: false          # Save community contribution data
+
+# Verification
+verify:
+  enabled: true
+  test_prompts: null         # null = use built-in test prompts
+  compute_perplexity: true
+  compute_kl: true