fix(voice): point pip install hint at venv pip instead of system Python

When Hermes runs inside its bundled venv (~/.hermes/profiles/<name>/
hermes-agent/venv/), the bare 'pip install sounddevice numpy' hint in
_voice_capture_install_hint() told users to install into whichever
Python their shell resolves first — on macOS that is often the system
Python under Rosetta, a completely separate site-packages tree with
incompatible wheel arches.

Detect venv via sys.prefix != sys.base_prefix and return the full path
to the venv's pip binary (Path(sys.prefix)/bin/pip) when available.
Falls back to the bare hint outside a venv (e.g. bare-metal installs).

Also adds 'from pathlib import Path' which was the only new import.

tools/voice_mode.py

@@ -18,6 +18,7 @@ import shlex
 import shutil
 import subprocess
 import sys
+from pathlib import Path
 import tempfile
 import threading
 import time
@@ -122,6 +123,19 @@ from hermes_constants import is_termux as _is_termux_environment
 def _voice_capture_install_hint() -> str:
     if _is_termux_environment():
         return "pkg install python-numpy portaudio && python -m pip install sounddevice"
+    # If we're running inside a venv (e.g. the bundled Hermes venv at
+    # ~/.hermes/profiles/<name>/hermes-agent/venv/), `pip install` on the
+    # user's PATH won't reach the right site-packages — the bare hint sends
+    # them off to whichever Python their shell resolves first, which on macOS
+    # is often a system Python under Rosetta with a totally separate wheel
+    # index. Point them at the actual interpreter pip is sitting next to.
+    try:
+        if sys.prefix != getattr(sys, "base_prefix", sys.prefix):
+            pip_in_venv = Path(sys.prefix) / "bin" / "pip"
+            if pip_in_venv.exists():
+                return f"{pip_in_venv} install sounddevice numpy"
+    except Exception:
+        pass
     return "pip install sounddevice numpy"