fix(tui): clickable hyperlinks and skill slash command dispatch

Two TUI fixes:

1. Hyperlinks are now clickable (Cmd+Click / Ctrl+Click) in terminals
   that support OSC 8.  The markdown renderer was rendering links as
   plain colored text — now wraps them in the existing <Link> component
   from @hermes/ink which emits OSC 8 escape sequences.

2. Skill slash commands (e.g. /hermes-agent-dev) now work in the TUI.
   The slash.exec handler was delegating to the _SlashWorker subprocess
   which calls cli.process_command().  For skills, process_command()
   queues the invocation message onto _pending_input — a Queue that
   nobody reads in the worker subprocess.  The skill message was lost.
   Now slash.exec detects skill commands early and rejects them so
   the TUI falls through to command.dispatch, which correctly builds
   and returns the skill payload for the client to send().

tests/tui_gateway/test_protocol.py

@@ -231,3 +231,51 @@ def test_cli_exec_blocked(server, argv):
 ])
 def test_cli_exec_allowed(server, argv):
     assert server._cli_exec_blocked(argv) is None
+
+
+# ── slash.exec skill command interception ────────────────────────────
+
+
+def test_slash_exec_rejects_skill_commands(server):
+    """slash.exec must reject skill commands so the TUI falls through to command.dispatch."""
+    # Register a mock session
+    sid = "test-session"
+    server._sessions[sid] = {"session_key": sid, "agent": None}
+
+    # Mock scan_skill_commands to return a known skill
+    fake_skills = {"/hermes-agent-dev": {"name": "hermes-agent-dev", "description": "Dev workflow"}}
+
+    with patch("agent.skill_commands.scan_skill_commands", return_value=fake_skills):
+        resp = server.handle_request({
+            "id": "r1",
+            "method": "slash.exec",
+            "params": {"command": "hermes-agent-dev", "session_id": sid},
+        })
+
+    # Should return an error so the TUI's .catch() fires command.dispatch
+    assert "error" in resp
+    assert resp["error"]["code"] == 4018
+    assert "skill command" in resp["error"]["message"]
+
+
+def test_command_dispatch_returns_skill_payload(server):
+    """command.dispatch returns structured skill payload for the TUI to send()."""
+    sid = "test-session"
+    server._sessions[sid] = {"session_key": sid}
+
+    fake_skills = {"/hermes-agent-dev": {"name": "hermes-agent-dev", "description": "Dev workflow"}}
+    fake_msg = "Loaded skill content here"
+
+    with patch("agent.skill_commands.scan_skill_commands", return_value=fake_skills), \
+         patch("agent.skill_commands.build_skill_invocation_message", return_value=fake_msg):
+        resp = server.handle_request({
+            "id": "r2",
+            "method": "command.dispatch",
+            "params": {"name": "hermes-agent-dev", "session_id": sid},
+        })
+
+    assert "error" not in resp
+    result = resp["result"]
+    assert result["type"] == "skill"
+    assert result["message"] == fake_msg
+    assert result["name"] == "hermes-agent-dev"