emrg: fix Windows installer DeleteFile code 5 — module-holder enumeration + isolated mode

[argszero]

Summary

Fixes the persistent Windows installer DeleteFile code 5 on ~/.emrg/install overwrite (host rants 2026-08-18T16:09:45 + 16:24:01, reproduced on v0.2.48).

Root causes (diagnostic-script proof, rant 16:24:01)

• The lock holder was PID 9280 — a browser-harness child process that loaded install\lib\websockets\speedups.pyd (inherited PYTHONPATH). Restart Manager never reported it (the 2 owners it found were excluded ancestors) → killing the wrong object.
• CreateFileW probing provably cannot detect DLL module locks: a DELETE + SHARE_NONE probe reported OK while DeleteFile still failed — LoadLibrary image-section locks are only visible via Process.Modules enumeration.
• stop_all.py ran from install\python-dist\python.exe whose site config could import install\lib → potential self-lock (rant 16:09:45).
• Kill-mode RM scan hit the 60s timeout (PowerShell Stop-Process hangs on refusing/waiting targets).

Fixes (emrg/_stop_all.py + packaging/make-installer.sh)

1. find_install_module_holders() — PowerShell Get-Process + $_.Modules.FileName filtered by the install prefix: names the actual processes holding DLL/.pyd locks (with loaded-file list, parent PID, excluded-ancestor tag).
2. stop_lock_owners() order — module-holder enumeration FIRST (kills each external holder's process tree via taskkill /F /T /PID), then Restart Manager as auxiliary; browser-harness hint preserved.
3. verify — new module-holder residual category (primary); RM re-scan + createfile-probe kept as auxiliary; any external holder → exit 1 with a named list → installer aborts cleanly.
4. createfile-probe demoted to supplementary — relabeled from the misleading "lock-probe 0 locked" (it cannot see DLL locks); real verdict comes from module-holders.
5. Isolated mode — installer runs stop_all with "{PythonExe}" -I "{StopScript}" (ignore PYTHONPATH/site-packages/.pth), so the pure-stdlib script never imports install\lib (self-lock eliminated).
6. Self-lock final guard — if the probe still reports locked files but neither module-holder nor RM found an external owner, print WARNING: lock holder is the stop_all runtime itself + exit 1 (re-run installer guidance) instead of letting the installer hit code 5.

Verification

• tests/test_stop_all.py + tests/test_installer_stop.py: 85 passed (new tests pin module-holder enumeration, taskkill /F /T, verify category order, createfile-probe demotion, self-lock guard).
• Full suite: 941 passed + 1 skipped (942 collected; Agent.md count updated).
• GUI npm test green; import + CLI OK.

Acceptance (Windows, next release)

stop_all.log shows module-holders: PID ... python.exe (...browser_harness.daemon) loads [speedups...] → killed with its tree → verify has no module-holder → installer overwrites install\ without code 5. Clean/quiet installs unaffected; rm-scan owner detail retained.

[argszero]

✅ LGTM — cycle (1/3). Both test + test-windows CI PASS (run 32116928996). Reviewed full diff: module-holder enumeration via Get-Process/.Modules (only detector for DLL image-section locks, per host diagnostic evidence PID 9280), taskkill /F /T tree kill, verify module-holder category primary + createfile-probe demoted (supplementary), -I isolated mode in PrepareToInstall (self-lock), self-lock final guard. Local pytest 941 passed + 1 skipped (942 collected), GUI green, import + CLI OK.

[argszero]

✅ LGTM — cycle (2/3). Independent re-verify: head 96ef83f unchanged, CI test + test-windows both PASS (run 32116928996), MERGEABLE CLEAN. Confirmed in diff: find_install_module_holders()/_parse_module_holders()/_kill_tree_windows() present; stop_lock_owners runs module-holder enumeration before RM; verify has module-holder category before RM re-scan; createfile-probe demoted to supplementary; PrepareToInstall runs python with -I isolated mode; self-lock guard (no external module-holder/RM owner → WARNING + exit 1).

[argszero]

✅ LGTM — cycle (3/3). Re-verified head 96ef83f (unchanged since 2/3), CI test + test-windows PASS (32116928996), MERGEABLE CLEAN. Three independent cycle reviews complete — merging.