docs: restructure AGENTS.md and slim CLAUDE.md

[chapel]

Summary

• Rewrite AGENTS.md from 287 → 488 lines to match kynetic-spec's lean-doc standard (PR #350)
• Add 20 sections covering: project identity, dual shadow branch architecture (.kspec/ + .kbot/), bot-specific architecture (ACP client, supervisor checkpoint protocol, memory persistence), kspec foundation (essential rules, task workflow, spec-first development), ralph loop mode, PR workflow, and troubleshooting
• Replace CLAUDE.md (68 lines of duplicated CLI reference) with single @AGENTS.md directive — all content migrated into AGENTS.md

Key additions vs previous AGENTS.md

• What This Project Is: 7-package monorepo overview with responsibilities
• Bot Architecture: Message flow diagram, ACP gotchas (single prompt per session, cancel fallback to SIGTERM), supervisor semantics (clean exit = no respawn, checkpoint protocol), memory auto-commit scheduling
• Ralph Loop Mode: Full loop description, task inheritance priority, blocking rules
• PR Workflow: 3-step lifecycle (/local-review → /pr → /pr-review), quality gates
• Running the Bot: Env var reference, AGENT_COMMAND split gotcha, strict integer parsing
• Troubleshooting: Expanded from 4 to 10 entries with bot-specific failure modes

Test plan

• wc -l AGENTS.md = 488 lines (target ~440, overshoot justified by bot-specific architecture)
• wc -l CLAUDE.md = 1 line
• Codex cross-review verified all MUST-FIX items addressed
• No code changes — docs only

Generated with Claude Code

[chapel]

Strong restructure overall: this is much closer to the reference AGENTS style and the flow is substantially clearer. I found one MUST-FIX factual mismatch and a few SHOULD-FIX/SUGGESTION items for accuracy/clarity.

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.