fix(security): replace real AWS account ID with placeholder

Replace account ID 107396990521 with standard placeholder 123456789012
in README.org examples. Remove hardcoded credential placeholders from
switch_profile.sh dev case — use AWS_PROFILE instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jwalsh

README.org

@@ -794,7 +794,7 @@ aws iam get-role --role-name AWSGlueServiceRole | jq -r '.Role.Arn' | tee /tmp/r
 #+end_src
 
 #+RESULTS:
-: arn:aws:iam::107396990521:role/AWSGlueServiceRole
+: arn:aws:iam::123456789012:role/AWSGlueServiceRole
 
 
 #+begin_src emacs-lisp 
@@ -803,7 +803,7 @@ aws iam get-role --role-name AWSGlueServiceRole | jq -r '.Role.Arn' | tee /tmp/r
 #+end_src
 
 #+RESULTS:
-: role_arn value: arn:aws:iam::107396990521:role/AWSGlueServiceRole
+: role_arn value: arn:aws:iam::123456789012:role/AWSGlueServiceRole
 
 #+begin_src shell
 echo "$role_arn" 
@@ -859,7 +859,7 @@ job.commit()
 #+begin_src shell
   aws glue create-job \
     --name mla-job \
-    --role arn:aws:iam::107396990521:role/AWSGlueServiceRole \
+    --role arn:aws:iam::123456789012:role/AWSGlueServiceRole \
     --command Name=glueetl,ScriptLocation=s3://aif-c01-jasonwalsh/scripts/glue-script.py \
     --output text
 #+END_SRC

scripts/switch_profile.sh

@@ -12,10 +12,10 @@ switch_profile() {
 		;;
 	dev)
 		export AWS_PROFILE=dev
-		export AWS_ACCESS_KEY_ID=your_aws_access_key_id
-		export AWS_SECRET_ACCESS_KEY=your_aws_secret_access_key
+		unset AWS_ACCESS_KEY_ID
+		unset AWS_SECRET_ACCESS_KEY
 		export AWS_DEFAULT_REGION=us-east-1
-		echo "Switched to AWS dev profile"
+		echo "Switched to AWS dev profile (uses AWS_PROFILE credentials)"
 		;;
 	*)
 		echo "Usage: switch_profile [lcl|dev]"