Puppeteer _resolve_installed_browser_path: fall back to newest mtime when no SemVer

Chromium build IDs (e.g. ``1618494``) aren't valid SemVer, so
``SemVer.parse`` returns ``None`` for all candidates. When two
builds end up in the cache (typical ``chromium@latest`` reinstall
flow: original build + newly-resolved ``latest``) we fell through
to ``return None`` because ``parsed_candidates=[]`` and
``len(candidates) > 1``. ``provider.install('chrome', no_cache=True)``
then failed the post-install load with "Installed package did not
produce runnable binary 'chrome'" — exactly the CI failure on
``test_chrome_alias_installs_real_browser_binary``.

Add a deterministic fallback: sort unparseable candidates by file
mtime and pick the newest, so a ``latest`` reinstall still resolves
to the freshly-downloaded build instead of bailing out.

Author: claude

abxpkg/binprovider_puppeteer.py

@@ -406,9 +406,21 @@ def _resolve_installed_browser_path(
         ]
         if parsed_candidates:
             return max(parsed_candidates, key=lambda item: item[0])[1]
+        if not candidates:
+            return None
         if len(candidates) == 1:
             return candidates[0][1]
-        return None
+        # Multiple cached builds but none parse as ``SemVer`` (e.g. chromium's
+        # integer build IDs like ``1618539``). Fall back to the newest one
+        # by file mtime so post-install lookups land on the freshly-
+        # downloaded version rather than ``None``.
+        candidates.sort(
+            key=lambda item: (
+                item[1].stat().st_mtime if item[1].exists() else 0,
+                item[0],
+            ),
+        )
+        return candidates[-1][1]
 
     def _refresh_symlink(self, bin_name: str, target: Path) -> Path:
         bin_dir = self.bin_dir