docs: update composer description and keywords

- Update description to full version (487 chars) with all major features
  Includes sharding, migrations, query macros, DDL builder, batch processing,
  PSR-14 events, and other recently added features

- Add missing keywords: sharding, migrations, query-macros, macro-system,
  ddl, schema-builder, lateral-join, query-profiling, query-compilation-cache,
  batch-processing, merge-statements, sql-formatter, sql-pretty-printer,
  connection-retry, psr-14, event-dispatcher, explain-analysis

Improves discoverability on Packagist and GitHub

Author: tommyknocker

composer.json

@@ -1,6 +1,6 @@
 {
   "name": "tommyknocker/pdo-database-class",
-  "description": "Lightweight PHP database library with unified API for MySQL, MariaDB, PostgreSQL & SQLite. QueryBuilder, caching, window functions, CTEs, JSON, ActiveRecord with validation, 80+ helpers.",
+  "description": "Lightweight, framework-agnostic PHP database library with unified API across MySQL, MariaDB, PostgreSQL & SQLite. Features: Fluent QueryBuilder, query caching (PSR-16), prepared statement pool, read/write splitting, sharding (range/hash/modulo), window functions, CTEs, JSON operations, migrations, DDL builder, ActiveRecord with validation, query macros, batch processing, 80+ helpers, PSR-14 events. Zero external dependencies, PHPStan level 8, fully tested.",
   "type": "library",
   "keywords": [
     "pdo",
@@ -26,6 +26,7 @@
     "read-write-splitting",
     "load-balancing",
     "master-replica",
+    "sharding",
     "window-functions",
     "cte",
     "common-table-expressions",
@@ -65,7 +66,24 @@
     "php8",
     "lightweight",
     "cross-platform",
-    "performance"
+    "performance",
+    "migrations",
+    "database-migrations",
+    "query-macros",
+    "macro-system",
+    "ddl",
+    "schema-builder",
+    "lateral-join",
+    "query-profiling",
+    "query-compilation-cache",
+    "batch-processing",
+    "merge-statements",
+    "sql-formatter",
+    "sql-pretty-printer",
+    "connection-retry",
+    "psr-14",
+    "event-dispatcher",
+    "explain-analysis"
   ],
   "homepage": "https://github.com/tommyknocker/pdo-database-class",
   "license": "MIT",