Added oblivious HTTP support

[ameshkov]

No description provided.

[Copilot]

Pull Request Overview

This PR adds Oblivious HTTP (OHTTP) support to gocurl, allowing users to send encrypted HTTP requests through an OHTTP gateway that provides enhanced privacy by hiding client identity from the target server.

Key changes:

• Added new command-line flags --ohttp-gateway-url and --ohttp-keys-url for OHTTP configuration
• Implemented oblivious HTTP transport layer with encryption/decryption capabilities
• Fixed logging output to use configurable writers instead of hardcoded stderr

Reviewed Changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
internal/config/options.go	Added OHTTP configuration options with gateway and keys URL fields
internal/config/config.go	Added OHTTP URL parsing and validation logic requiring both options together
internal/client/transport.go	Added conditional routing to OHTTP transport when OHTTP URLs are configured
internal/client/ohttp.go	Implemented complete OHTTP transport with encryption, gateway communication, and decryption
internal/output/output.go	Fixed logging methods to use configurable log writer instead of hardcoded stderr
internal/cmd/cmd_test.go	Added comprehensive test coverage for OHTTP functionality and proxy integration
go.mod	Added ohttp-go library dependency
README.md	Added comprehensive OHTTP documentation with usage examples
CHANGELOG.md	Added changelog entry for new OHTTP features

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[Copilot]

Pull Request Overview

Copilot reviewed 10 out of 11 changed files in this pull request and generated no new comments.

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