Publish canonical Claude and Codex plugins

[saldestechnology]

Summary

• commit canonical v0.3.4 Claude and Codex plugin trees under plugins/claude/ctx and plugins/codex/ctx
• add complete public metadata and GitHub/release installation documentation
• make CI compare committed trees byte-for-byte with fresh harness output and validate both plugin formats
• package future release ZIPs from the committed canonical trees after drift checks

Validation

• cargo test (passes outside the macOS sandbox; 9 provider tests cannot initialize SystemConfiguration inside it)
• cargo clippy -- -D warnings
• cargo fmt --all -- --check
• ./scripts/release-plugin-check.sh --check
• claude plugin validate ./plugins/claude/ctx --strict
• clean temporary CODEX_HOME: marketplace add, plugin install, and plugin list all succeed for ctx@ctx-local v0.3.4
• claude --plugin-dir ./plugins/claude/ctx reaches the authentication boundary; this environment has no Claude login, so an authenticated interactive smoke test remains unavailable

MCP disclosure

The published default trees and v0.3.4 release ZIPs do not include .mcp.json. Documentation states that MCP requires installing/building ctx with --features mcp.