Add preliminary support for protobuf formatting

[ryanfowler]

No description provided.

[Copilot]

Pull request overview

This PR adds preliminary support for formatting protobuf responses in the fetch tool. When responses are received with protobuf content types, the tool will now parse and display them in a human-readable format with color-coded field numbers, wire types, and values.

Changes:

• Added protobuf formatting logic with support for varint, fixed32, fixed64, bytes, and nested message wire types
• Integrated protobuf detection and formatting into the response handling pipeline
• Added the google.golang.org/protobuf dependency for protobuf parsing
• Updated documentation to reflect the new protobuf formatting capability

Reviewed changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
internal/format/protobuf.go	Implements protobuf formatting with wire type detection, nested message handling, and colored output
internal/format/protobuf_test.go	Comprehensive test suite covering all wire types, nested messages, edge cases, and helper functions
internal/fetch/fetch.go	Adds TypeProtobuf constant and integrates protobuf formatting into response handling and content-type detection
go.mod	Adds google.golang.org/protobuf v1.36.11 dependency
docs/USAGE.md	Documents protobuf as a supported format with content-type examples
README.md	Updates feature list to include protobuf in formatted output types

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