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"],
+  "contributors": []
+}
+

concepts/streams/about.md

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+# About
+
+Streams in Java offer a modern, functional approach to processing data. Instead of writing verbose loops, you can build pipelines that transform collections with clarity and elegance.
+
+Streams are built on three key components:
+
+1. **Source** – Typically a collection like a `List` or `Set`.
+2. **Intermediate Operations** – Transformations such as `filter`, `map`, or `sorted`.
+3. **Terminal Operation** – Produces a result, like `collect`, `count`, or `forEach`.
+
+```java
+List<String> names = List.of("Dharshini", "Naveen", "Selena");
+
+List<String> filtered = names.stream()
+    .filter(name -> name.startsWith("N"))
+    .collect(Collectors.toList());
+
+// => ["Naveen"]
+```
+
+
+[Java Stream API Overview]:https://docs.oracle.com/javase/8/docs/api/java/util/stream/package-summary.html
+[Collectors Class]:https://docs.oracle.com/javase/8/docs/api/java/util/stream/Collectors.html
+[Java Functional Programming with Streams]:https://www.baeldung.com/java-8-streams
+[Stream Operations Explained]:https://www.geeksforgeeks.org/stream-in-java/

concepts/streams/introduction.md

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+# Introduction
+
+Imagine you’re at an airport, watching suitcases glide past on a conveyor belt. You don’t grab every bag—you scan for yours, maybe sort by color or tag, and pick only what you need. That’s how Java Streams work.
+
+Instead of writing loops and mutating variables, you describe *what* you want to do with the data. Want to filter out expensive items? Map names to uppercase? Count how many entries match a condition? Streams make it all feel natural.
+
+Streams are part of Java’s functional programming toolkit. They help you write code that’s:
+- **Declarative** – Focused on intent, not mechanics.
+- **Composable** – Easy to chain operations.
+- **Lazy** – Efficient by computing only when needed.
+
+Once you start using streams, you’ll find yourself writing fewer loops and more elegant pipelines. It’s not just cleaner—it’s fun.
+

concepts/streams/links.json

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+[
+  {
+    "url": "https://docs.oracle.com/javase/8/docs/api/java/util/stream/package-summary.html",
+    "description": "Java Stream API Overview"
+  },
+  {
+    "url": "https://docs.oracle.com/javase/8/docs/api/java/util/stream/Collectors.html",
+    "description": "Collectors Class"
+  },
+  {
+    "url": "https://www.baeldung.com/java-8-streams",
+    "description": "Java Functional Programming with Streams"
+  },
+  {
+    "url": "https://www.geeksforgeeks.org/stream-in-java/",
+    "description": "Stream Operations Explained"
+  }
+]