fix(concepts): rename value-reference-types to primitives-objects
Replace misleading 'Value vs Reference Types' concept page with
accurate 'Primitives vs Objects' terminology per ECMAScript spec.
Key changes:
- Use ECMAScript terminology (primitives/objects, not value/reference types)
- Explain 'call by sharing' semantics instead of pass-by-value/reference
- Debunk stack/heap storage myth as implementation detail
- Add V8 internals section explaining Smis and heap allocation
- Update all internal links across 10 files
- Rename test directory and update tests with new terminology
- Add redirect from old URL to new URL
Addresses GitHub issue #481 about spreading misinformation.
All 59 tests passing. Fact-checked against MDN, ECMAScript spec,
and expert sources (Dmitry Soshnikov, Barbara Liskov's call-by-sharing).