Fix Windows Cookbook background tasks, exit statuses, and empty SSH logs wrapper (#1389)

This commit consolidates all Windows Cookbook background fixes into a single comprehensive commit based on the latest main branch.

Key fixes included:
1. React looksSuccessful Mismatch: Append 'DOWNLOAD_OK' for pip install commands in routes/cookbook_routes.py.
2. Local Windows SSH Wrapper & Log Directory Mismatch: Bypassed ssh wrappers and dynamically selected odysseus-tmux logs for local tasks in static/js/cookbookRunning.js.
3. WSL Bash Filtration: Filtered out the WSL bash stub at C:\Windows\System32\bash.exe in core/platform_compat.py.
4. Drive-Colon Path Normalization: Replaced .as_posix() with git_bash_path() in routes/shell_routes.py and src/bg_jobs.py.
5. GGUF-Only Hardware Fitting: Restructured local Windows recommendations to rank GGUF only in services/hwfit/fit.py.
6. Safe Win32 Process Liveness Probe: Replaced os.kill(pid, 0) with a safe Win32 API probe using GetExitCodeProcess in core/platform_compat.py.
7. Prebuilt llama-cpp-python Wheels: Supply the CPU extra index during compilation failure fallback.
8. Enforce UTF-8 log encoding: Set PYTHONIOENCODING=utf-8 on Windows bootstrap runners.
9. Fix Linux Llama.cpp Build script syntax error in routes/cookbook_helpers.py.
10. Page Reload Status Check: Run sys.executable instead of 'python3' to bypass Microsoft Store execution stubs on local Windows hosts.
11. Llama.cpp serve build bypass: Bypassed cmake compilation checks on local Windows and verified python bindings directly.
12. Serve Command Path Validation: Masked safe GGUF path printf subshells '' inside the serve command validator.
13. CPU Mismatch Diagnostics: Intercepted AVX2-lacking '0xc000001d' (Illegal Instruction) crashes in static/js/cookbook-diagnosis.js and guided users to Ollama.
14. Windows Pytest stability: Fixed stub import leakage in test files.

src/bg_jobs.py

@@ -33,6 +33,7 @@ from core.atomic_io import atomic_write_json
 from core.platform_compat import (
     detached_popen_kwargs,
     find_bash,
+    git_bash_path,
     kill_process_tree,
     pid_alive,
 )
@@ -106,7 +107,7 @@ def launch(command: str, session_id: str, cwd: Optional[str] = None,
         # handles drive paths and spaces correctly.
         cmd_path = _JOBS_DIR / f"{job_id}.cmd.sh"
         cmd_path.write_text(command + "\n", encoding="utf-8")
-        lp, xp, cp = (shlex.quote(p.as_posix()) for p in (log_path, exit_path, cmd_path))
+        lp, xp, cp = (shlex.quote(git_bash_path(p)) for p in (log_path, exit_path, cmd_path))
         script_path = _JOBS_DIR / f"{job_id}.sh"
         script_path.write_text(
             f"bash {cp} > {lp} 2>&1\n"