feat: add GitHub Copilot CLI host adapter

[konard]

Summary

• add the native GitHub Copilot CLI .plugin/plugin.json manifest and camelCase hooks configuration
• route all Copilot hooks through the shared Archcore scripts from the user project root
• normalize captured native file-tool paths and archcore-* MCP tool names without changing the behavior pinned for existing hosts
• add real redacted Copilot CLI 1.0.73 payload fixtures, structural/unit regressions, release documentation, and the four-manifest 0.4.23 version bump

Reproduction and root cause

The prepared adapter still encoded provisional Copilot payload assumptions. Live captures showed that native create/edit calls put the file in an absolute path field rather than file_path, and Copilot exposes the Archcore MCP update tool as archcore-update_document rather than the shared canonical name. In addition, hooks without an explicit project-relative cwd execute from the installed plugin directory.

The normalizer now maps those native payloads into the existing internal contract, and the Copilot hook file pins cwd: ".", ARCHCORE_HOST=copilot, native lifecycle keys, mutation-tool matchers, and bounded pre/post hook execution.

Verification

• make all — JSON, permissions, ShellCheck, and all 385 Bats tests pass
• make test-codex-smoke — all 5 Codex marketplace/install/runtime smoke tests pass
• live Copilot CLI 1.0.73 smoke: a direct .archcore/*.md create is denied and no target is written
• live Copilot CLI 1.0.73 smoke: project-root post-tool cascade context reaches the model
• live Copilot CLI 1.0.73 smoke: top-level session additionalContext reaches the model in an empty project
• live native MCP payload capture verifies the archcore-update_document normalization regression

Upstream dependencies found during live testing

Two end-to-end acceptance gaps are outside this plugin adapter and now have focused upstream reports:

• Emit native session-start output for GitHub Copilot CLI hooks cli#27 — Archcore CLI 0.5.7 emits the Claude hookSpecificOutput envelope for archcore hooks copilot session-start; Copilot requires top-level additionalContext
• Plugin MCP servers cannot resolve the active project directory github/copilot-cli#4234 — plugin MCP children start in the plugin install directory and receive neither the project path nor MCP roots, so the shared Archcore MCP process cannot select the user's project

The adapter and its independently testable protections are ready for review; initialized-project session context and project-correct MCP operation remain gated by those upstream fixes.

Addresses #24

[konard]

Replacement PR: https://github.com/archcore-ai/plugin/pull/27\n\nPR 26 cannot be reopened because GitHub froze its pre-dev head SHA, which has no common ancestry with the dev base. The prepared branch now contains the completed, dev-based implementation; PR 27 preserves that branch and supersedes this closed draft.