Python: Harness console for python (#6312)

* Add initial harness console for python

* Add textual to project

* Add planning and approval flows with list selector

* Address PR comments

* Fix list selection bug

* Fix PR #6312 round 2 review comments

- Escape untrusted agent text with rich.markup.escape() in observers
  (text_output, planning_output, reasoning_display) to prevent markup injection
- Remove non-functional 'Always approve' choices from tool_approval.py
  (framework lacks CreateAlwaysApproveToolResponse support)
- Remove textual from root pyproject.toml dev deps (sample-specific)
- Add PEP 723 inline script metadata to harness_research.py
- Narrow except Exception to except NoMatches in list_selection.py

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix build error

* Fix build errors

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/samples/02-agents/harness/console/components/mode_help.py

@@ -0,0 +1,48 @@
+# Copyright (c) Microsoft. All rights reserved.
+
+"""Agent mode and help text display widget."""
+
+from __future__ import annotations
+
+from rich.text import Text
+from textual.reactive import reactive
+from textual.widgets import Static
+
+
+class AgentModeAndHelp(Static):
+    """Widget displaying the current agent mode and help text.
+
+    Shows the current agent mode (e.g., "plan", "execute") in a colored label,
+    followed by available commands and help text in a dimmed style. Used in
+    the fixed bottom area of the console.
+
+    Attributes:
+        mode: Current mode name (e.g., "plan", "execute"), or None if no mode.
+        mode_color: Rich color string for the mode label (e.g., "yellow", "green").
+        help_text: Help text to display (e.g., "/exit to quit, /mode to switch").
+    """
+
+    mode: reactive[str | None] = reactive(None)
+    mode_color: reactive[str] = reactive("yellow")
+    help_text: reactive[str] = reactive("")
+
+    def render(self) -> Text:
+        """Render the mode indicator and help text.
+
+        Returns:
+            Rich Text object with styled mode and help display.
+        """
+        result = Text()
+
+        if self.mode:
+            result.append(f"[{self.mode}]", style=self.mode_color)
+
+        if self.help_text:
+            if self.mode:
+                result.append("  ")
+            result.append(self.help_text, style="dim")
+
+        if not result.plain:
+            result.append(" ")
+
+        return result