Add CLAUDE.md to provide agent context for code and triage tasks

What happened

PR #964 was a human-authored change that required no agent involvement. However, reviewing the repo's fullsend configuration revealed that while the repo has a mature agent setup — 6 roles enabled (triage, coder, review, fix, retro, prioritize), Jira integration polling every 5 minutes for ROSAENG issues with component = osdctl, custom sandbox network policies, and issues actively labeled ready-to-code (#943, #941) — it has no CLAUDE.md, .claude/ directory, or AGENTS.md file. The harness configs at .fullsend/harness/code.yaml and .fullsend/harness/triage.yaml extend upstream fullsend-ai/agents@v0.38.0 but provide no repo-specific context beyond Jira credentials.

What could go better

When code or triage agents are dispatched for this Go CLI project, they currently have no repo-specific guidance about build commands (make build, make test, make lint, make format), project structure, testing conventions, or coding standards. The agents must discover these through exploration, which increases token cost, rework risk, and time to resolution. This is high-confidence — the repo clearly uses agents for real work (Jira-driven triage, ready-to-code labeled issues), and the absence of context files is a straightforward gap. The CI workflow files modified in this PR show that the project uses Prow for CI (build, format, lint, test, verify-docs checks), GoReleaser for releases, and COPR for RPM builds — all context that would help agents navigate the project.

Proposed change

Create a CLAUDE.md file at the repository root covering at minimum:

1. Build and test commands — make build, make test, make lint, make format, make verify-docs (derived from the Prow CI checks visible in the PR status checks).
2. Project overview — Go CLI tool (osdctl) for OpenShift Dedicated cluster operations, built with GoReleaser.
3. Code structure — key directories, command registration pattern, and how new commands are added.
4. Testing conventions — unit test expectations, any integration test patterns.
5. PR conventions — Prow-based review process using OWNERS files and /lgtm + /approve commands; merge handled by openshift-merge-bot.

Keep the file concise (under 60 lines per platform guidelines). Focus on information that helps agents write correct code on the first attempt — build commands, test commands, and common pitfalls.

Validation criteria

After CLAUDE.md is added, the next 3 code agent runs on this repo should: (1) use the documented build/test commands without needing to discover them through exploration, (2) produce PRs that pass make lint and make format on the first commit without requiring fix agent intervention, and (3) show reduced token usage in the exploration phase compared to prior code agent runs (if any exist for baseline comparison).

Generated by retro agent from https://github.com/openshift/osdctl/pull/964

Start by reading .fullsend/harness/code.yaml and .fullsend/harness/triage.yaml, then review the build, test, lint, format, and verify-docs checks referenced in the issue and PR #964. Add a concise root CLAUDE.md under 60 lines covering the requested project, workflow, testing, and PR conventions, and ensure it documents the listed commands and validation expectations.