feat(gateway): skill-aware slash commands, paginated /commands, Telegram 100-cap (#3934)

* feat(gateway): skill-aware slash commands, paginated /commands, Telegram 100-cap

Map active skills to Telegram's slash command menu so users can
discover and invoke skills directly. Three changes:

1. Telegram menu now includes active skill commands alongside built-in
   commands, capped at 100 entries (Telegram Bot API limit). Overflow
   commands remain callable but hidden from the picker. Logged at
   startup when cap is hit.

2. New /commands [page] gateway command for paginated browsing of all
   commands + skills. /help now shows first 10 skill commands and
   points to /commands for the full list.

3. When a user types a slash command that matches a disabled or
   uninstalled skill, they get actionable guidance:
   - Disabled: 'Enable it with: hermes skills config'
   - Optional (not installed): 'Install with: hermes skills install official/<path>'

Built on ideas from PR #3921 by @kshitijk4poor.

* chore: move 21 niche skills to optional-skills

Move specialized/niche skills from built-in (skills/) to optional
(optional-skills/) to reduce the default skill count. Users can
install them with: hermes skills install official/<category>/<name>

Moved skills (21):
- mlops: accelerate, chroma, faiss, flash-attention,
  hermes-atropos-environments, huggingface-tokenizers, instructor,
  lambda-labs, llava, nemo-curator, pinecone, pytorch-lightning,
  qdrant, saelens, simpo, slime, tensorrt-llm, torchtitan
- research: domain-intel, duckduckgo-search
- devops: inference-sh cli

Built-in skills: 96 → 75
Optional skills: 22 → 43

* fix: only include repo built-in skills in Telegram menu, not user-installed

User-installed skills (from hub or manually added) stay accessible via
/skills and by typing the command directly, but don't get registered
in the Telegram slash command picker. Only skills whose SKILL.md is
under the repo's skills/ directory are included in the menu.

This keeps the Telegram menu focused on the curated built-in set while
user-installed skills remain discoverable through /skills and /commands.

optional-skills/mlops/chroma/references/integration.md

@@ -0,0 +1,38 @@
+# Chroma Integration Guide
+
+Integration with LangChain, LlamaIndex, and frameworks.
+
+## LangChain
+
+```python
+from langchain_chroma import Chroma
+from langchain_openai import OpenAIEmbeddings
+
+vectorstore = Chroma.from_documents(
+    documents=docs,
+    embedding=OpenAIEmbeddings(),
+    persist_directory="./chroma_db"
+)
+
+# Query
+results = vectorstore.similarity_search("query", k=3)
+
+# As retriever
+retriever = vectorstore.as_retriever()
+```
+
+## LlamaIndex
+
+```python
+from llama_index.vector_stores.chroma import ChromaVectorStore
+import chromadb
+
+db = chromadb.PersistentClient(path="./chroma_db")
+collection = db.get_or_create_collection("docs")
+
+vector_store = ChromaVectorStore(chroma_collection=collection)
+```
+
+## Resources
+
+- **Docs**: https://docs.trychroma.com