Add ci and lint move to camelCase JSON

[Soph]

• get all linting to be green as a base line
• add proper ci jobs
• make JSON output consitent camelCase

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Note

Medium Risk
Changes the public JSON output shape from snake_case to camelCase, which is a breaking change for any consumers. Also touches core git protocol/strategy codepaths with expanded error wrapping and stricter error handling, which could surface new failures in edge cases.

Overview
Adds GitHub Actions workflows for test, lint (including golangci-lint), and a reusable license check, plus a repo-wide .golangci.yaml to baseline linting.

Standardizes all CLI/embedding JSON output fields to camelCase (updates struct tags, docs, and tests/bench JSON assertions), and tightens error handling across auth/token storage, git protocol fetch/push, planner, and strategies by wrapping/propagating errors and handling write/close failures more explicitly (introducing testify/require for cleaner test assertions).

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