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>

agent/prompt_builder.py

@@ -330,28 +330,34 @@ def build_skills_system_prompt(
     # Each entry: (skill_name, description)
     # Supports sub-categories: skills/mlops/training/axolotl/SKILL.md
     # -> category "mlops/training", skill "axolotl"
+    # Load disabled skill names once for the entire scan
+    try:
+        from tools.skills_tool import _get_disabled_skill_names
+        disabled = _get_disabled_skill_names()
+    except Exception:
+        disabled = set()
+
     skills_by_category: dict[str, list[tuple[str, str]]] = {}
     for skill_file in skills_dir.rglob("SKILL.md"):
-        is_compatible, _, desc = _parse_skill_file(skill_file)
+        is_compatible, frontmatter, desc = _parse_skill_file(skill_file)
         if not is_compatible:
             continue
-        # Skip skills whose conditional activation rules exclude them
-        conditions = _read_skill_conditions(skill_file)
-        if not _skill_should_show(conditions, available_tools, available_toolsets):
-            continue
         rel_path = skill_file.relative_to(skills_dir)
         parts = rel_path.parts
         if len(parts) >= 2:
-            # Category is everything between skills_dir and the skill folder
-            # e.g. parts = ("mlops", "training", "axolotl", "SKILL.md")
-            #   → category = "mlops/training", skill_name = "axolotl"
-            # e.g. parts = ("github", "github-auth", "SKILL.md")
-            #   → category = "github", skill_name = "github-auth"
             skill_name = parts[-2]
             category = "/".join(parts[:-2]) if len(parts) > 2 else parts[0]
         else:
             category = "general"
             skill_name = skill_file.parent.name
+        # Respect user's disabled skills config
+        fm_name = frontmatter.get("name", skill_name)
+        if fm_name in disabled or skill_name in disabled:
+            continue
+        # Skip skills whose conditional activation rules exclude them
+        conditions = _read_skill_conditions(skill_file)
+        if not _skill_should_show(conditions, available_tools, available_toolsets):
+            continue
         skills_by_category.setdefault(category, []).append((skill_name, desc))
 
     if not skills_by_category: