fix bug in subst.entry-index.sh, improve awk scripts

Fixed a bug that was introduced into `bin/subst.entry-index.sh`
where the value `$HTML_SED` was set too early.  Shell functions
variables are evaluated when they are executed, not when they
are first parsed.  So exported variables used by a shell function
need to be set only before the shell function is executed.

Checkpoint `bin/cvt-submission.sh` as part of our testing.
Set file modes of 0444 for when `.auth.json` is formed from `.auth.json.xz`.

The awk scripts under bin put their name (basename) into error
messages to make it easier to debug any error they might raise.

Changed `bin/cvt-submission.sh` VERSION from "2.0.1 2025-05-01"
to "2.0.2 2025-05-17".

Changed `bin/filelist.entry.json.awk` VERSION from "1.0 2024-02-12"
to "1.0.1 2025-05-17".

Changed `bin/manifest.csv.entry.awk` VERSION from "1.0 2024-07-14"
to "1.0.1 2025-05-17".

Changed `bin/manifest.entry.json.awk` VERSION from "1.2.1 2024-11-16"
to "1.2.2 2025-05-17".

Changed `bin/subst.entry-index.sh` VERSION from "2.0.0 2025-03-13"
to "2.0.1 2025-05-17".

Changed `bin/subst.entry-navbar.awk` VERSION from "1.3 2024-08-02"
to "1.3.1 2025-05-17".

Changed `bin/subst.year-navbar.awk` VERSION from "1.2 2024-04-04"
to "1.2.1 2025-05-17".

Update sitemap.

Tested the above via `make update` on macOS.

bin/md2html.sh

@@ -1,5 +1,4 @@
 #!/usr/bin/env bash
-
 #
 # md2html.sh - convert markdown into an IOCCC HTML file via config file
 #