fix: disabled skills respected across banner, system prompt, slash commands, and skill_view (#1897)

* fix: banner skill count now respects disabled skills and platform filtering

The banner's get_available_skills() was doing a raw rglob scan of
~/.hermes/skills/ without checking:
- Whether skills are disabled (skills.disabled config)
- Whether skills match the current platform (platforms: frontmatter)

This caused the banner to show inflated skill counts (e.g. '100 skills'
when many are disabled) and list macOS-only skills on Linux.

Fix: delegate to _find_all_skills() from tools/skills_tool which already
handles both platform gating and disabled-skill filtering.

* fix: system prompt and slash commands now respect disabled skills

Two more places where disabled skills were still surfaced:

1. build_skills_system_prompt() in prompt_builder.py — disabled skills
   appeared in the <available_skills> system prompt section, causing
   the agent to suggest/load them despite being disabled.

2. scan_skill_commands() in skill_commands.py — disabled skills still
   registered as /skill-name slash commands in CLI help and could be
   invoked.

Both now load _get_disabled_skill_names() and filter accordingly.

* fix: skill_view blocks disabled skills

skill_view() checked platform compatibility but not disabled state,
so the agent could still load and read disabled skills directly.

Now returns a clear error when a disabled skill is requested, telling
the user to enable it via hermes skills or inspect the files manually.

---------

Co-authored-by: Test <test@test.com>

hermes_cli/banner.py

@@ -102,27 +102,22 @@ COMPACT_BANNER = """
 # =========================================================================
 
 def get_available_skills() -> Dict[str, List[str]]:
-    """Scan ~/.hermes/skills/ and return skills grouped by category."""
-    import os
+    """Return skills grouped by category, filtered by platform and disabled state.
 
-    hermes_home = Path(os.getenv("HERMES_HOME", Path.home() / ".hermes"))
-    skills_dir = hermes_home / "skills"
-    skills_by_category = {}
-
-    if not skills_dir.exists():
-        return skills_by_category
-
-    for skill_file in skills_dir.rglob("SKILL.md"):
-        rel_path = skill_file.relative_to(skills_dir)
-        parts = rel_path.parts
-        if len(parts) >= 2:
-            category = parts[0]
-            skill_name = parts[-2]
-        else:
-            category = "general"
-            skill_name = skill_file.parent.name
-        skills_by_category.setdefault(category, []).append(skill_name)
+    Delegates to ``_find_all_skills()`` from ``tools/skills_tool`` which already
+    handles platform gating (``platforms:`` frontmatter) and respects the
+    user's ``skills.disabled`` config list.
+    """
+    try:
+        from tools.skills_tool import _find_all_skills
+        all_skills = _find_all_skills()  # already filtered
+    except Exception:
+        return {}
 
+    skills_by_category: Dict[str, List[str]] = {}
+    for skill in all_skills:
+        category = skill.get("category") or "general"
+        skills_by_category.setdefault(category, []).append(skill["name"])
     return skills_by_category