fix(validate): fix unzip hanging on password-protected ZIPs via setsid

unzip -tq on a password-protected archive tries to open /dev/tty to
prompt for the password. Inside a tmux session this generates SIGTTIN,
which stops the process (ps state T). A stopped process cannot receive
SIGTERM, so timeout waited indefinitely for a child that would never exit.

Fix: wrap all unzip calls with setsid so the process runs in a new
session without a controlling terminal. The /dev/tty open then fails
immediately with ENXIO and unzip exits with a non-zero code instead of
blocking. Additional hardening:
- timeout -k 5: send SIGKILL 5 s after SIGTERM as a last resort
- < /dev/null: also cut off stdin as a secondary safeguard
- exit 137 (128+9, SIGKILL) treated as timeout alongside 124
- error output matching "password"/"encrypt"/"need PK compat" reported
  as UNVERIFIED instead of INVALID

Affects: recover_bad_signature.sh, restore_bad_signature.sh,
         recreate_bad_signature.sh

recover_bad_signature.sh

@@ -360,20 +360,32 @@ validate_recovered_file() {
          if [[ "$_head8o" = "d0cf11e0a1b11ae1" ]] ; then
             echo "VALID|OLE2/CFBF container signature ok - this is a password-protected Office file (encrypted package), not a plain zip, so the zip check does not apply; open it with the password to verify content"
          elif command -v unzip > /dev/null 2>&1 ; then
-            # Use a 120-second timeout: unzip -tq on a very large or partially
-            # corrupt ZIP can block indefinitely otherwise (the process simply
-            # stalls in I/O, unlike a clean CRC error which exits quickly).
+            # Run unzip inside setsid so it has no controlling terminal.
+            # Without setsid, a password-protected ZIP causes unzip to try
+            # opening /dev/tty to prompt for the password. When running in
+            # the background of a tmux session this generates SIGTTIN, which
+            # STOPS the process (ps state T). A stopped process cannot receive
+            # SIGTERM, so timeout hangs indefinitely waiting for a child that
+            # will never exit. With setsid the /dev/tty open fails immediately
+            # with ENXIO and unzip exits with a non-zero code instead.
+            # -k 5: send SIGKILL 5 s after SIGTERM in case the process is
+            # still alive (e.g. stopped or in uninterruptible sleep).
             local _unzip_exit
-            timeout 120 unzip -tq "$_f" > /dev/null 2>&1
+            timeout -k 5 120 setsid unzip -tq "$_f" < /dev/null > /dev/null 2>&1
             _unzip_exit=$?
             if [[ $_unzip_exit -eq 0 ]] ; then
                echo "VALID|zip integrity ok"
-            elif [[ $_unzip_exit -eq 124 ]] ; then
+            elif [[ $_unzip_exit -eq 124 || $_unzip_exit -eq 137 ]] ; then
+               # 124 = killed by SIGTERM after timeout, 137 = killed by SIGKILL (128+9)
                echo "UNVERIFIED|zip integrity check timed out after 120 s (file may be very large or corrupt; check manually with: unzip -t \"$_f\")"
             else
                local _badentry
-               _badentry="$(trim "$(timeout 120 unzip -t "$_f" 2>&1 | grep -v '^Archive:' | grep -v '^[[:space:]]*$' | head -1)")"
-               echo "INVALID|zip integrity check failed${_badentry:+ (${_badentry})}"
+               _badentry="$(trim "$(timeout -k 5 120 setsid unzip -t "$_f" < /dev/null 2>&1 | grep -v '^Archive:' | grep -v '^[[:space:]]*$' | head -1)")"
+               if echo "$_badentry" | grep -qi "password\|encrypt\|need PK compat" ; then
+                  echo "UNVERIFIED|zip is password-protected (cannot verify without password${_badentry:+; unzip says: ${_badentry}})"
+               else
+                  echo "INVALID|zip integrity check failed${_badentry:+ (${_badentry})}"
+               fi
             fi
          else
             echo "UNVERIFIED|unzip not installed"