strings: Java Strings deep dive companion code (pool/intern, indy concat vs StringBuilder JMH, text blocks, string templates)

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01KqJyCidz3ZgRyHABv2GVJh

strings/output/01-string-pool.txt

@@ -0,0 +1,9 @@
+literal == literal          : true
+literal == new String       : false
+literal.equals(new String)  : true
+literal == c.intern()       : true
+constant + literal == "hello" : true
+runtime concat == "hello"     : false
+runtime concat.intern() == "hello": true
+built "java".intern() == the built instance : false
+built unseen string .intern() == the built instance: true