`Pymode` correctly detected/activated virtualenvs, but `:PymodeRun` still executed code with Vim's embedded/system Python, causing version mismatch (e.g. active 3.13 venv, output from 3.14 system Python).
This change aligns run behavior with virtualenv activation so executed code uses the selected environment interpreter.

• Run-path correction for virtualenv-enabled sessions

  • Updated `pymode/run.py` so `run_code()` checks `g:pymode_virtualenv_enabled` and resolves the venv Python executable (`bin/python` on Unix, `Scripts/python.exe` on Windows).
  • When available, code is executed via that interpreter through a temp script + subprocess, preserving cwd and capturing stdout/stderr for existing quickfix/output flow.
  • Keeps existing in-process execution path as fallback when no active virtualenv interpreter is available.

• Correctness fixes

  • `file` is now set to the real source file path inside the subprocess (previously resolved to the temp file path, breaking code that uses `file` at runtime).
  • Subprocess tracebacks have the temp file path replaced with the real source path so error messages point to the correct file.
  • Explicit UTF-8 encoding passed to `subprocess.Popen`.
  • Added `g:pymode_run_timeout` (default `0` = no limit) to prevent Vim from hanging if a script never terminates; `TimeoutExpired` is caught, the process is killed, and an error message is appended.
  • Pre-existing bug fixed: `sys.stdout`/`sys.stderr` are now restored before returning early on a non-zero `SystemExit`.

• Regression coverage

  • Added a focused Vader test in `tests/vader/commands.vader` that:
    • creates a temporary virtualenv,
    • activates it with `:PymodeVirtualenv`,
    • runs `:PymodeRun`,
    • asserts `run` output includes the venv interpreter path.
  • Fixed `string(venv_dir)` → `fnameescape(venv_dir)` in the test (`string()` wraps the path in quotes, producing a malformed argument).
  • Test now saves and restores `g:pymode_virtualenv_enabled` / `g:pymode_virtualenv` so it does not pollute subsequent tests.
  • Cleanup (`delete`) and state restore run unconditionally regardless of whether venv creation succeeded.

• Docs update

  • Clarified in `doc/pymode.txt` that `:PymodeRun` uses the virtualenv Python executable when a virtualenv is activated.
  • Added `g:pymode_run_timeout` default in `plugin/pymode.vim`.

```python

before: often printed system interpreter from Vim host runtime

import sys
print(sys.executable)

after: with :PymodeVirtualenv .venv, prints .../.venv/bin/python (or Scripts/python.exe)

```