feat: add streams concept

concepts/streams/.meta/config.json

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+{
+  "blurb": "Java Streams provide a powerful way to process collections using a functional approach.",
+  "authors": ["Navaneedan S"],
+  "contributors": []
+}
+

concepts/streams/about.md

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+# About Streams
+
+**Streams** are a functional abstraction for processing sequences of data in Java.
+Unlike collections like [`List`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/List.html), a [`Stream`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/stream/Stream.html) does not store elements—it describes a pipeline of operations to transform or compute data.
+
+Streams are typically created from collections, arrays, or manually using `Stream.of(...)`.
+
+For example:
+
+```java
+Stream<String> emptyStream = Stream.of();
+Stream<Integer> singleInteger = Stream.of(1);
+Stream<Boolean> threeBooleans = Stream.of(true, false, true);
+Stream<Object> mixedTypes = Stream.of("hello", 1, true); // allowed in Stream<Object>
+```
+
+
+[Java Stream API Overview]:https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/stream/package-summary.html
+[Collectors Class]:https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/stream/Collectors.html
+[Stream Interface Documentation]:https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/stream/Stream.html
+[Stream Operations Explained]:https://www.geeksforgeeks.org/stream-in-java/

concepts/streams/introduction.md

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+# Introduction to Streams
+
+**Streams** are part of Java’s functional programming toolkit. They allow you to process collections in a declarative style—focusing on *what* to do, not *how* to do it.
+
+You can create streams from collections like `List`, `Set`, or arrays, and then apply operations like `filter`, `map`, and `reduce` to transform or analyze the data.
+
+## Examples
+
+### Filtering a List
+```java
+List<String> names = List.of("Akash", "James", "Charles");
+List<String> filtered = names.stream()
+                             .filter(name -> name.startsWith("A"))
+                             .collect(Collectors.toList());
+// filtered is ["Akash"]

concepts/streams/links.json

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+[
+  {
+    "url": "https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/stream/package-summary.html",
+    "description": "Java Stream API Overview"
+  },
+  {
+    "url": "https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/stream/Collectors.html",
+    "description": "Collectors Class"
+  },
+  {
+    "url": "https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/stream/Stream.html",
+    "description": "Stream Interface Documentation"
+  },
+  {
+    "url": "https://www.geeksforgeeks.org/stream-in-java/",
+    "description": "Stream Operations Explained"
+  }
+]