chore: bump version to 0.3.0 and rename package to s5js

- Rename package from 's5' to 's5js' for clarity
- Version: 0.3.0 (Phase 6 completion)
- Phase 6: Advanced Media Processing complete
- Phase 6.5: Advanced CID API complete (74 tests)
- Phase 7: Testing & Performance 85% complete
- Bundle size: 60.09 KB compressed (10x under requirement)
- Total: 280+ tests passing across 30+ test files
- Tarball: s5js-0.3.0.tgz ready for Sia Foundation Phase 6 review

Author: Developer

package-lock.json

@@ -1,12 +1,18 @@
 {
-  "name": "s5",
-  "version": "0.2.0",
+  "name": "s5js",
+  "version": "0.3.0",
   "type": "module",
   "description": "Use S5",
   "main": "./dist/src/index.js",
   "module": "./dist/src/index.js",
   "types": "./dist/src/index.d.ts",
   "sideEffects": false,
+  "files": [
+    "dist/",
+    "README.md",
+    "LICENSE",
+    "package.json"
+  ],
   "exports": {
     ".": {
       "types": "./dist/src/index.d.ts",