feat(tools): centralize tool emoji metadata in registry + skin integration

- Add 'emoji' field to ToolEntry and 'get_emoji()' to ToolRegistry
- Add emoji= to all 50+ registry.register() calls across tool files
- Add get_tool_emoji() helper in agent/display.py with 3-tier resolution:
  skin override → registry default → hardcoded fallback
- Replace hardcoded emoji maps in run_agent.py, delegate_tool.py, and
  gateway/run.py with centralized get_tool_emoji() calls
- Add 'tool_emojis' field to SkinConfig so skins can override per-tool
  emojis (e.g. ares skin could use swords instead of wrenches)
- Add 11 tests (5 registry emoji, 6 display/skin integration)
- Update AGENTS.md skin docs table

Based on the approach from PR #1061 by ForgingAlex (emoji centralization
in registry). This salvage fixes several issues from the original:
- Does NOT split the cronjob tool (which would crash on missing schemas)
- Does NOT change image_generate toolset/requires_env/is_async
- Does NOT delete existing tests
- Completes the centralization (gateway/run.py was missed)
- Hooks into the skin system for full customizability

hermes_cli/skin_engine.py

@@ -60,6 +60,12 @@ All fields are optional. Missing values inherit from the ``default`` skin.
     # Tool prefix: character for tool output lines (default: ┊)
     tool_prefix: "┊"
 
+    # Tool emojis: override the default emoji for any tool (used in spinners & progress)
+    tool_emojis:
+      terminal: "⚔"           # Override terminal tool emoji
+      web_search: "🔮"        # Override web_search tool emoji
+      # Any tool not listed here uses its registry default
+
 USAGE
 =====
 
@@ -111,6 +117,7 @@ class SkinConfig:
     spinner: Dict[str, Any] = field(default_factory=dict)
     branding: Dict[str, str] = field(default_factory=dict)
     tool_prefix: str = "┊"
+    tool_emojis: Dict[str, str] = field(default_factory=dict)  # per-tool emoji overrides
     banner_logo: str = ""    # Rich-markup ASCII art logo (replaces HERMES_AGENT_LOGO)
     banner_hero: str = ""    # Rich-markup hero art (replaces HERMES_CADUCEUS)
 
@@ -541,6 +548,7 @@ def _build_skin_config(data: Dict[str, Any]) -> SkinConfig:
         spinner=spinner,
         branding=branding,
         tool_prefix=data.get("tool_prefix", default.get("tool_prefix", "┊")),
+        tool_emojis=data.get("tool_emojis", {}),
         banner_logo=data.get("banner_logo", ""),
         banner_hero=data.get("banner_hero", ""),
     )