fix: align PHP RPC autoload namespaces

[manuelsampedro1]

The package currently mixes the old Denpa\Bitcoin namespace with the forked naftalimurgor\Bitgesell namespace. As a result, Composer's PSR-4 autoload map does not match most source and test classes, and the configured response handler points at a class name that does not match its file/class.

Changes:

• update Composer package metadata and PSR-4 roots to the Bitgesell namespace used by the source tree
• move Config into the Bitgesell namespace and update the client provider
• point the response handler at the actual BitcoindResponse class name
• align the response test namespace/imports with the Bitgesell test namespace
• refresh remaining Bitgesell Core docblocks touched by this path

Validation:

• node -e "JSON.parse(require('fs').readFileSync('composer.json','utf8'))"
• rg check for stale Denpa namespace / BitgeselldResponse references in composer.json, src, and tests
• git diff --check

Note: I could not run Composer/PHP tests locally because this environment does not have PHP or Composer installed.

Bounty context: BitgesellOfficial/bitgesell#39

[MyTH-zyxeon]

Review-assist note for the Bitgesell #81 improvement lane.

I checked the public PR body and diff. This is a focused PHP RPC package correctness fix:

• aligns composer.json package metadata and PSR-4 roots with the forked naftalimurgor\Bitgesell namespace used by the source tree
• moves Config into the Bitgesell namespace expected by the client provider
• points the response handler at the actual BitcoindResponse class/file instead of the stale BitgeselldResponse name
• updates the response test namespace/imports so Composer dev autoloading and PHPUnit discovery can target the same namespace shape

Suggested maintainer checks before merge:

• run composer validate --strict
• run composer dump-autoload
• run the package test suite, or at minimum the response test touched by this patch
• search composer.json, src, and tests for stale Denpa\Bitcoin and BitgeselldResponse references
• decide whether the package name should stay under naftalimurgor or be updated to an official Bitgesell vendor before publishing

From the public patch shape, this looks like a useful low-risk Composer/autoload repair candidate for the #81 improvement queue. I did not run Composer, PHP, RPC, payment, or live-chain actions for this review-assist note.