fix(android): raise the versionCode floor so 0.5.x can install over v0.5.2

v0.5.2 shipped Android versionCode 5002, from an earlier `minor*1000` scheme.
The `minor*100` formula that replaced it yields only 1502 for that same version,
and 1503 for 0.5.3 — lower than what is already installed, so Android refuses
the update as a downgrade. Every 0.5.x release built from this script was
un-installable for anyone already on v0.5.2.

This is the exact failure the block was written to prevent; its floor simply
went stale. The floor tracked "codes below 1000 are already in the field", which
was true when written, but a 5002 build has shipped since — and the highest code
this formula has *produced* is not the same as the highest code in the field.

Widen the multipliers and raise the floor past 5002:

    code = 10000 + major*1000000 + minor*1000 + patch

    0.0.14 -> 10014    0.5.2 -> 15002    0.6.0 -> 16000
    0.1.0  -> 11000    0.5.3 -> 15003    1.0.0 -> 1010000

Still strictly monotonic across the upgrade sequence. The guard test gains a
case pinning 0.5.3 above the 5002 in the field, so the floor is expressed as
"clears what shipped" rather than a literal that can silently go stale again.

scripts/set-version.sh

@@ -81,8 +81,16 @@ fi
 # builds shipped versionCode 1000 (from a 0.1.0 config), so a plain 15 is a
 # *downgrade* and Android refuses the update.
 #
-#   code = 1000 + major*10000 + minor*100 + patch
-# e.g. 0.0.14 -> 1014, 0.0.15 -> 1015, 0.1.0 -> 1100, 1.0.0 -> 11000.
+# The floor has to clear the highest code actually in the field, which is not the
+# same as the highest this formula has produced. v0.5.2 shipped versionCode
+# **5002** under an earlier `minor*1000` scheme; the `minor*100` formula that
+# replaced it yields only 1502 for that same version, and 1503 for 0.5.3 — so
+# every 0.5.x release built from it was an un-installable downgrade for anyone
+# already on v0.5.2, which is exactly the failure this block exists to prevent.
+# The multipliers are widened and the floor raised past 5002 accordingly.
+#
+#   code = 10000 + major*1000000 + minor*1000 + patch
+# e.g. 0.0.14 -> 10014, 0.1.0 -> 11000, 0.5.3 -> 15003, 1.0.0 -> 1010000.
 PROPS="src-tauri/gen/android/app/tauri.properties"
 if [ -f "$PROPS" ]; then
   # Strip any -rc1/+build suffix first: it is not numeric, and feeding it to
@@ -93,7 +101,7 @@ if [ -f "$PROPS" ]; then
   MIN=$(echo "$CORE" | cut -d. -f2)
   PAT=$(echo "$CORE" | cut -d. -f3)
   : "${MAJ:=0}" "${MIN:=0}" "${PAT:=0}"
-  CODE=$(( 1000 + MAJ*10000 + MIN*100 + PAT ))
+  CODE=$(( 10000 + MAJ*1000000 + MIN*1000 + PAT ))
   echo "   versionCode=$CODE (from $CORE)"
   if grep -q '^tauri.android.versionCode=' "$PROPS"; then
     sed -i "s/^tauri.android.versionCode=.*/tauri.android.versionCode=$CODE/" "$PROPS"