Add secrets module: Spring Cloud Vault, AWS Secrets Manager, Kubernetes configtree and Jasypt on Spring Boot 4.1.2, with real transcripts

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_017ic4b6tTs7ivgTNq4ZrurU

secrets/output/10-exposure.txt

@@ -0,0 +1,12 @@
+1. the jar: src/main/resources/application-leaky.yml (a deliberately committed secret) as packaged
+   $ unzip -p target/secrets-1.0.0.jar BOOT-INF/classes/application-leaky.yml | grep password
+     password: hunter2-committed-to-git
+2. command-line argument, as any user on the host sees it
+   $ ps -o args= -p <pid> | tr ' ' '\n' | grep db.password
+   --db.password=arg-secret-789
+3. environment variables, readable by the same user
+   $ tr '\0' '\n' < /proc/<pid>/environ | grep -E 'DB_PASSWORD_FROM_ENV|SIGNING_KEY'
+   DB_PASSWORD_FROM_ENV=env-secret-123
+   SIGNING_KEY=env-signing-key-456
+4. /proc/<pid>/cmdline, what the kernel keeps of the arguments
+   --db.password=arg-secret-789