refactor: replace numeric translation keys with named keys

- Extract shared i18n.sh library with tr() function (replaces 5 duplicated text_lang functions)
- Replace numeric IDs (001, 002, ...) with human-readable keys (already_started, delete, etc.)
- Update all language files (en_US, en_GB, de_DE) to use named key format
- Update all scripts (jdautoenc, rename, addrename, removerename, config) to use tr() from i18n.sh

jdautoenc.sh

@@ -1,10 +1,10 @@
 #!/bin/bash
 
-JDAutoConfig=$(find ~ -type f -name "JDAutoConfig" 2>/dev/null)
-log=$(grep "log=" "$JDAutoConfig" | sed 's/.*=//g')
+config=$(find ~ -type f -name "JDAutoConfig" 2>/dev/null)
+log=$(grep "log=" "$config" | sed 's/.*=//g')
 
 # shellcheck disable=SC1090
-source "$JDAutoConfig"
+source "$config"
 
 # shellcheck disable=SC1091
 source "$(dirname "$0")/i18n.sh"

rename.sh

@@ -14,7 +14,6 @@ count=$(($3 + 1))
 # shellcheck disable=SC1090
 source "$config"
 
-JDAutoConfig="$config"
 # shellcheck disable=SC1091
 source "$(dirname "$0")/i18n.sh"