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.

hermes_cli/commands.py

@@ -118,6 +118,8 @@ COMMAND_REGISTRY: list[CommandDef] = [
                "Tools & Skills", cli_only=True),
 
     # Info
+    CommandDef("commands", "Browse all commands and skills (paginated)", "Info",
+               gateway_only=True, args_hint="[page]"),
     CommandDef("help", "Show available commands", "Info"),
     CommandDef("usage", "Show token usage for the current session", "Info"),
     CommandDef("insights", "Show usage insights and analytics", "Info",
@@ -361,6 +363,47 @@ def telegram_bot_commands() -> list[tuple[str, str]]:
     return result
 
 
+def telegram_menu_commands(max_commands: int = 100) -> tuple[list[tuple[str, str]], int]:
+    """Return Telegram menu commands (built-in + active skills), capped to the Bot API limit.
+
+    Built-in commands come first, then active skill commands.  Commands beyond
+    ``max_commands`` remain callable in the gateway; they are just omitted from
+    Telegram's native slash-command picker.
+
+    Returns:
+        (menu_commands, hidden_count) where hidden_count is the number of
+        commands omitted due to the cap.
+    """
+    all_commands = list(telegram_bot_commands())
+
+    # Append active BUILT-IN skill commands only (not user-installed hub skills).
+    # User-installed skills stay accessible via /skills and by typing the command
+    # directly, but don't clutter the Telegram menu.
+    try:
+        from agent.skill_commands import get_skill_commands
+        from pathlib import Path
+        # The repo's built-in skills live under <repo>/skills/
+        _repo_skills_dir = str(Path(__file__).resolve().parent.parent / "skills")
+        skill_cmds = get_skill_commands()
+        for cmd_key in sorted(skill_cmds):
+            info = skill_cmds[cmd_key]
+            # Only include skills whose SKILL.md is in the repo's skills/ dir
+            skill_path = info.get("skill_md_path", "")
+            if not skill_path.startswith(_repo_skills_dir):
+                continue
+            name = cmd_key.lstrip("/").replace("-", "_")
+            desc = info.get("description", "")
+            # Telegram descriptions max 256 chars
+            if len(desc) > 256:
+                desc = desc[:253] + "..."
+            all_commands.append((name, desc))
+    except Exception:
+        pass
+
+    hidden_count = max(0, len(all_commands) - max_commands)
+    return all_commands[:max_commands], hidden_count
+
+
 def slack_subcommand_map() -> dict[str, str]:
     """Return subcommand -> /command mapping for Slack /hermes handler.