Add fresher-qa module: 50 Java interview questions for freshers, one runnable demo each, asserted transcripts, javac error captures

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_017ic4b5DfjBGLBr7F5km2AN

fresher-qa/output/03-strings.txt

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+=== Q21 == vs equals() on Strings ===
+a == b      -> true
+a == c      -> false
+a.equals(c) -> true
+=== Q22 Why is String immutable? ===
+s     = java
+upper = JAVA
+same object returned when nothing changes: true
+=== Q23 String vs StringBuilder vs StringBuffer ===
+builder result: cba-
+append is synchronized: StringBuffer=true, StringBuilder=false
+=== Q24 The string pool, compile-time constants and intern() ===
+"hel" + "lo" == "hello"      -> true
+"hel" + lo == "hello"        -> false
+"hel" + finalLo == "hello"   -> true
+("hel" + lo).intern() == "hello" -> true
+=== Q25 Reverse a string and check for a palindrome ===
+weivretni
+true
+false
+=== Q26 Useful String methods and the split() surprises ===
+trim().length()  = 6
+strip().length() = 2
+"   ".isBlank() = true, "ab".repeat(3) = ababab
+"a,b,,".split(",").length     = 2
+"a,b,,".split(",", -1).length = 4
+String.join: 2026-11-11
+=== Q27 Count characters, find the first non-repeating one, check anagrams ===
+frequency: {s=3, w=1, i=1}
+first non-repeating: w
+listen/silent anagrams: true