feat(cli): restore live per-tool elapsed timer in TUI spinner (#7359)

Brings back the live elapsed time counter that was lost when the CLI
transitioned from raw KawaiiSpinner animation to prompt_toolkit TUI.

The original implementation (Feb 2026) used KawaiiSpinner per tool call
with \r-based animation showing '(4.2s)' ticking up live. When
patch_stdout was introduced, the \r animation was disabled and replaced
with a static _spinner_text widget that only showed the tool name.

Now the spinner widget shows elapsed time again:
  💻 git log --oneline  (3.2s)

Implementation:
- Track _tool_start_time (monotonic) on tool.started events
- Clear it on tool.completed and thinking transitions
- get_spinner_text() computes live elapsed on each TUI repaint
- The existing poll loop already invalidates every ~0.15s, so no
  extra timer thread is needed

Addresses #4287.

cli.py

@@ -1719,6 +1719,7 @@ class HermesCLI:
         self._secret_state = None
         self._secret_deadline = 0
         self._spinner_text: str = ""  # thinking spinner text for TUI
+        self._tool_start_time: float = 0.0  # monotonic timestamp when current tool started (for live elapsed)
         self._command_running = False
         self._command_status = ""
         self._attached_images: list[Path] = []
@@ -2130,6 +2131,7 @@ class HermesCLI:
         if not text:
             self._flush_reasoning_preview(force=True)
         self._spinner_text = text or ""
+        self._tool_start_time = 0.0  # clear tool timer when switching to thinking
         self._invalidate()
 
     # ── Streaming display ────────────────────────────────────────────────
@@ -6145,11 +6147,20 @@ class HermesCLI:
         Updates the TUI spinner widget so the user can see what the agent
         is doing during tool execution (fills the gap between thinking
         spinner and next response).  Also plays audio cue in voice mode.
+
+        On tool.started, records a monotonic timestamp so get_spinner_text()
+        can show a live elapsed timer (the TUI poll loop already invalidates
+        every ~0.15s, so the counter updates automatically).
         """
-        # Only act on tool.started; ignore tool.completed, reasoning.available, etc.
+        if event_type == "tool.completed":
+            import time as _time
+            self._tool_start_time = 0.0
+            self._invalidate()
+            return
         if event_type != "tool.started":
             return
         if function_name and not function_name.startswith("_"):
+            import time as _time
             from agent.display import get_tool_emoji
             emoji = get_tool_emoji(function_name)
             label = preview or function_name
@@ -6158,6 +6169,7 @@ class HermesCLI:
             if _pl > 0 and len(label) > _pl:
                 label = label[:_pl - 3] + "..."
             self._spinner_text = f"{emoji} {label}"
+            self._tool_start_time = _time.monotonic()
             self._invalidate()
 
         if not self._voice_mode:
@@ -8359,6 +8371,17 @@ class HermesCLI:
             txt = cli_ref._spinner_text
             if not txt:
                 return []
+            # Append live elapsed timer when a tool is running
+            t0 = cli_ref._tool_start_time
+            if t0 > 0:
+                import time as _time
+                elapsed = _time.monotonic() - t0
+                if elapsed >= 60:
+                    _m, _s = int(elapsed // 60), int(elapsed % 60)
+                    elapsed_str = f"{_m}m {_s}s"
+                else:
+                    elapsed_str = f"{elapsed:.1f}s"
+                return [('class:hint', f'  {txt}  ({elapsed_str})')]
             return [('class:hint', f'  {txt}')]
 
         def get_spinner_height():
@@ -8893,6 +8916,7 @@ class HermesCLI:
                     finally:
                         self._agent_running = False
                         self._spinner_text = ""
+                        self._tool_start_time = 0.0
 
                         app.invalidate()  # Refresh status line