chore: drop redundant apm-marketplace-check and Copilot marketplace mirror (findings 1, 2)

apm-marketplace-check checked network reachability of remote marketplace
refs, but finding 35 already removed the only remote package entry, so
every marketplace.packages[] source is local and the hook is pure
overlap with apm-pack-check-clean. apm-audit-ci was re-examined and kept
as-is -- its pre-commit-config.yaml comment already carries a dated,
verified justification the audit had missed.

check-marketplace-mirror-sync guarded .github/plugin/marketplace.json
against drift from .claude-plugin/marketplace.json. Verified against
current GitHub Copilot CLI docs: Copilot's marketplace discovery already
falls back through .github/plugin/marketplace.json to
.claude-plugin/marketplace.json, which this repo generates anyway -- the
dedicated mirror bought a discovery-order preference, not a capability.
Deleted the mirror file, its sync script, its test, and the hook.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YR2CjVumUbEGWcMikcoXBD

scripts/sync-marketplace-mirror.sh

@@ -1,81 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-# .claude-plugin/marketplace.json is apm's compiled Claude marketplace output (see
-# apm.yml's marketplace.outputs.claude). GitHub Copilot CLI's manifest lookup accepts
-# that same file at .claude-plugin/marketplace.json directly, but also has a legacy
-# convention path at .github/plugin/marketplace.json (see
-# plugins/kyberforge/docs/research/docs/github-copilot-plugins/marketplace.md) -- and
-# that path is a mirror of the Claude output, not a separate apm output profile (this
-# repo declares only the "claude" output). This script keeps that legacy mirror
-# byte-identical to .claude-plugin/marketplace.json instead of letting it silently
-# drift (see issue #90 comment thread).
-
-# Hard error, not a `|| pwd` fallback. Every path this script touches hangs off
-# REPO_ROOT, and both of its exits-0 paths are "the files agree" or "neither file
-# exists" -- so a REPO_ROOT pointing somewhere that is not this repo reports "no
-# drift" over a tree it never looked at. Run `--check` from an empty directory
-# outside any worktree and the fallback made that the literal outcome: rev-parse
-# failed, REPO_ROOT became $PWD, neither file was there, exit 0. Refusing to guess
-# is the only answer that cannot be silently wrong; the `-f "$DST"` branch below
-# covers a genuinely stale mirror, which is a different condition.
-if ! REPO_ROOT="$(git rev-parse --show-toplevel 2>/dev/null)" || [[ -z "$REPO_ROOT" ]]; then
-  echo "Error: not inside a git worktree -- cannot locate the repository root, and guessing \$PWD would let --check report \"no drift\" over a tree it never inspected. Run this from within the repository." >&2
-  exit 1
-fi
-SRC="$REPO_ROOT/.claude-plugin/marketplace.json"
-DST="$REPO_ROOT/.github/plugin/marketplace.json"
-
-usage() {
-  echo "Usage: $0 [--check]" >&2
-  exit 1
-}
-
-CHECK=0
-if [[ "${1:-}" == "--check" ]]; then
-  CHECK=1
-  shift
-fi
-[[ $# -eq 0 ]] || usage
-
-if [[ ! -f "$SRC" ]]; then
-  # A missing source with a surviving mirror is drift, not absence: the mirror
-  # can only be stale (nothing is left for it to be byte-identical to), which is
-  # precisely the silent divergence this script exists to prevent. Exiting 0
-  # here would report "no drift" over a mirror of a file that no longer exists.
-  # (An unresolvable REPO_ROOT is handled above and is a hard error; this branch
-  # is only about a source file that is genuinely gone from a real worktree.)
-  # scripts/sync-plugin-content.sh --check --all already errors on the same
-  # condition ("requires .../marketplace.json"); this matches it.
-  # Neither file present stays a genuine no-op: nothing to mirror, nothing stale.
-  if [[ "$CHECK" -eq 1 && -f "$DST" ]]; then
-    echo "DRIFT $DST: mirror exists but .claude-plugin/marketplace.json does not" >&2
-    echo "Fix: restore .claude-plugin/marketplace.json (apm's compiled Claude marketplace output), or delete $DST" >&2
-    exit 1
-  fi
-  exit 0
-fi
-
-if [[ "$CHECK" -eq 1 ]]; then
-  if [[ ! -f "$DST" ]] || ! diff -q "$SRC" "$DST" >/dev/null 2>&1; then
-    echo "DRIFT $DST: out of sync with .claude-plugin/marketplace.json" >&2
-    # The runnable command gets a line to ITSELF, and the rationale gets its own
-    # echo. It was one line -- `Fix: bash scripts/sync-marketplace-mirror.sh --
-    # apm ships no output profile...` -- which put the prose after `--`, the
-    # POSIX end-of-options marker, so copy-pasting the Fix line ran this script
-    # with ~24 stray argv entries: `${1:-}` was `--` (so CHECK stayed 0 and no
-    # shift happened), `[[ $# -eq 0 ]]` failed, and the tool meant to fix the
-    # drift answered with its own usage error and exit 1. The backticks around
-    # `apm pack` made it worse: the paste also command-substituted a real
-    # `apm pack` run before the script was even reached. Hence plain quotes
-    # below too. Keep the command alone on its line.
-    echo "Fix: run, from the repository root:" >&2
-    echo "  bash scripts/sync-marketplace-mirror.sh" >&2
-    echo "Note: apm ships no output profile targeting this path, so 'apm pack' does not refresh it. Expecting it to is exactly the drift this script and its pre-push hook exist to prevent." >&2
-    exit 1
-  fi
-  exit 0
-fi
-
-mkdir -p "$(dirname "$DST")"
-cp "$SRC" "$DST"

scripts/sync-plugin-content.sh

@@ -196,9 +196,9 @@ if [[ "$ALL" -eq 1 ]]; then
   # duplicate at every call site (see .pre-commit-config.yaml's
   # check-plugin-content-sync).
   #
-  # Hard error rather than a `|| pwd` fallback, on scripts/sync-marketplace-mirror.sh's
-  # reasoning: --all's entire work list hangs off REPO_ROOT, so a REPO_ROOT pointing at
-  # something that is not this repo checks a plugin set that is not this repo's. Run
+  # Hard error rather than a `|| pwd` fallback: --all's entire work list hangs off
+  # REPO_ROOT, so a REPO_ROOT pointing at something that is not this repo checks a
+  # plugin set that is not this repo's. Run
   # from outside a worktree the fallback happens to hit the `--all requires ...` error
   # below instead -- but only by accident, because $PWD had no marketplace.json in it;
   # $PWD holding an unrelated one is the case that would silently "pass".