add sha1sums maintenance script + freebsd-arm64 and linux-x86_64 runtime additions

- src/build_sha1sums.tcl: the checksum regeneration script AGENTS.md references (sums git-tracked artifacts per platform folder, reports NEW/SAME/CHANGED)
- freebsd-arm64/tclkit-851-freebsd7-x86_64 (+ new sha1sums.txt)
- linux-x86_64/tclkit-902-Linux64-intel-dyn_basic (sha1sums.txt updated)

Assisted-by: harness=claude; primary-model=claude-fable-5; api-location=anthropic.com

freebsd-arm64/sha1sums.txt

@@ -0,0 +1 @@
+a08dd02077733a7c0efa733dcfc4990a2e989122 *tclkit-851-freebsd7-x86_64

linux-x86_64/sha1sums.txt

@@ -1 +1,2 @@
 41c81c8cf4020ea67a4e0238c96f9550bdadd8c3 *tclkit-902-Linux64-intel-dyn
+a0c299db0429e799833eb77d7962f410c9a2bfb1 *tclkit-902-Linux64-intel-dyn_basic

src/build_sha1sums.tcl

@@ -0,0 +1,114 @@
+package require sha1
+set srcdir [file dirname [file normalize [info script]]]
+set basedir [file dirname $srcdir]
+puts stdout "processing using base folder $basedir"
+
+set rootfolders [glob -dir $basedir -types {d} -tail *]
+set os_list [list linux macosx win32 freebsd netbsd dragonflybsd]
+set known_skip_tails [list src test]
+set skip_extensions [list .md .txt]
+set original_cwd [pwd]
+set R   "\x1b\[31m" ;#Red
+set G   "\x1b\[32m" ;#Green
+set Y   "\x1b\[33m" ;#Yellow
+set C   "\x1b\[36m" ;#Cyan
+set RST "\x1b\[m"   ;#reset
+
+proc do_sha1_in_folder {binaryfolder level} {
+    global R G Y C RST skip_extensions
+    set indent [string repeat " " $level]
+    puts stdout "${indent}${C}[string repeat - 50]$RST"
+    if {$level == 0} {
+        puts stdout "${indent}Processing runtime folder $binaryfolder"
+    } else {
+        puts stdout "${indent}Processing sub folder $binaryfolder"
+    }
+
+    #temp
+    if {$level > 0} {
+        #return
+    }
+
+    set shafile [file join $binaryfolder sha1sums.txt]
+    set existing_sha_dict [dict create]
+    if {[file exists $shafile]} {
+        puts stdout "${indent}Existing sha1sums.txt found"
+        set fd [open $shafile r]
+        set existing_sha_data [read $fd]
+        close $fd
+        foreach ln [split $existing_sha_data \n] {
+            set trimln [string trim $ln]
+            if {$trimln eq ""} {continue}
+            set first_sp [string first " " $trimln]
+            set h [string range $trimln 0 $first_sp-1]
+            set tag [string range $trimln $first_sp+1 end]
+            # e.g *tclkit where * indicates binary was used
+            # or possibly a space instead of * (same output as unix 'sha1sum -b <filename>')
+            dict set existing_sha_dict [string range $tag 1 end] $h
+        }
+
+    } else {
+        puts stdout "${indent}No current sha1sums.txt file"
+    }
+
+    set candidate_file_tails [glob -nocomplain -dir $binaryfolder -type f -tail *]
+    cd $binaryfolder
+    set git_files [exec git ls-files --exclude-standard ":(glob)*"] 
+    set new_sha_dict [dict create]
+    foreach ftail $candidate_file_tails {
+        if {[string tolower [file extension $ftail]] in $skip_extensions} {continue}
+        if {$ftail in $git_files} {
+            set hash [sha1::sha1 -hex -filename [file join $binaryfolder $ftail]]
+            dict set new_sha_dict $hash $ftail
+        } else {
+            puts stdout "${indent}${R}Skipping $ftail$RST (not in result of 'git ls-files --exclude-standard :(glob)*')"
+        }
+    }
+    set changes 0
+    dict for {h f} $new_sha_dict {
+        if {[dict exists $existing_sha_dict $f]} {
+            if {$h ne [dict get $existing_sha_dict $f]} {
+                puts -nonewline stdout "${indent}${Y}*UPD*$RST $h $f\n"
+                incr changes
+            } else {
+                puts -nonewline stdout "${indent}SAME  $h *$f$RST\n"
+            }
+        } else {
+            puts -nonewline stdout "${indent}${G}*NEW*$RST $h *$f\n"
+            incr changes
+        }
+    }
+    if {[dict size $existing_sha_dict] != [dict size $new_sha_dict] || $changes > 0} {
+        puts stderr "${indent}rewriting sha file at $shafile"
+        set fd [open $shafile w]
+        dict for {h f} $new_sha_dict {
+            puts -nonewline $fd "$h *$f\n"
+        }
+        close $fd
+    } else {
+        puts stderr "${indent}No changes or additions detected"
+    }
+    set subfolder_tails [glob -nocomplain -dir $binaryfolder -type d -tail *]
+    foreach sftail $subfolder_tails {
+        if {[string match .* $sftail]} {
+            continue
+        }
+        do_sha1_in_folder [file join $binaryfolder $sftail] [expr {$level + 1}]
+    }
+}
+
+
+set level 0
+foreach dirtail $rootfolders {
+    set level 0
+    set indent ""
+    if {$dirtail in $known_skip_tails} {continue}
+    set firstword [lindex [split $dirtail -] 0]
+    if {$firstword ni $os_list} {
+        puts stderr "skipping unrecognised folder: $f"
+        continue
+    }
+    set runtimefolder [file join $basedir $dirtail]
+    do_sha1_in_folder $runtimefolder 0
+}
+cd $original_cwd