ci: drop the remaining Claude workflows

[AlexeyShalaev]

Follow-up to #59, which removed claude-review.yml after establishing that the credential behind it no longer buys a model call: the run initialised and ended in under two seconds with is_error: true, num_turns: 1, total_cost_usd: 0 and an empty modelUsage.

The other five authenticate with the same token. They raise no pull request checks because they trigger on issues, comments and manual dispatch, so nothing has been red — they would simply fail the first time anyone triggered them. This removes claude-agent-teams-implement.yml, claude-agent-teams-research.yml, claude-mentions.yml, claude-pm.yml and claude-triage.yml.

Everything under .claude/ stays. The rules, skills, commands, agent definitions and CLAUDE.md are for local Claude Code sessions and never needed CI or a repository secret. CONTRIBUTING.md still points at .claude/rules/ and that link still works.

Two files described the workflows that are going, so they are corrected rather than left dangling: the CI section of .claude/agent-teams-ai-setup.md now says what actually remains in .github/workflows/ and why the rest went, and the DevOps prompt inside .claude/mr-review-team.json no longer advertises removed workflows or the Agent Teams CI settings that went with them. The JSON still parses.

If the token is refreshed later, these workflows are a git revert away — but they were written for a repository layout that is not this one (the reviewer routing in the removed claude-review.yml keyed on libs/python/, frontend/ and apps/), so rewriting beats restoring.

[AlexeyShalaev]

Correction pushed. The first commit listed a release-please.yml among the surviving workflows; there is no such file here. Release Please runs from release.yml, and the two notes now name it, alongside ci.yml, docs.yml and publish.yml.