SMB: filename safety + hidden attrs; drop http://my-computer host browser (#354)

SMB share:
- Mark dotfiles HIDDEN and host junk (.DS_Store, Thumbs.db, ...) HIDDEN+SYSTEM
  so Explorer hides them by default but View > Show all files still works.
- Guard DOS device names (CON/PRN/AUX/NUL/CLOCK$/COM1-9/LPT1-9) in both the
  long name and the generated 8.3 name; covers nul.tar.gz and 'con .txt' too.
- Replace trailing dot/space runs with '_' so names don't alias their stripped
  form; block DEL and C1 control bytes.
- Fix duplicate listing of sanitized names (sfnMap was mutated mid-iteration).
- Thread attrs through OPEN/QUERY/FIND replies via DirEntry.attr / hostAttrs().
- New [5d] section in test-standalone.ts; 55 tests pass.

http file server:
- Remove the http://my-computer/ host-filesystem browser now that SMB covers
  folder sharing. fileserver.ts now serves only static/www at http://windows95/
  with a sep-suffixed traversal guard.
- Delete page-directory-listing.ts, page-error.ts, encoding.ts, hide-files.ts
  and the three isFileServer* settings keys (and unused SettingsManager.delete).
- Point static/www/apps.htm at the SMB share instead.

static/www/apps.htm

@@ -11,7 +11,7 @@
           <hr>
 
           <p>I've installed a few apps and games for you to try out. Check out the Games folder on the desktop!</p>
-          <p>If you want to try other games, I recommend trying to find them on the Internet Archive. On your host computer, visit https://archive.org, then find the "Classic PC Games" category. Once downloaded, you can import them into windows95 from <a href="http://my-computer">your host's Download folder</a>.</p>
+          <p>If you want to try other games, I recommend trying to find them on the Internet Archive. On your host computer, visit https://archive.org, then find the "Classic PC Games" category. Once downloaded, you can import them into windows95 from the network share &mdash; open <b>Network Neighborhood</b> on the desktop (or drive <b>Z:</b> after running <code>\\HOST\TOOLS\_MAPZ.BAT</code>).</p>
         </font>
       </td>
     </tr>