feat(harness): P3 per-run ABRA_DIR — structural recipe-tree isolation, recipe flock deleted

- run_recipe_ci.setup_run_abra_dir(): builds <runs_dir>/<run-id>/abra with servers/ and
  catalogue/ symlinked to the canonical ~/.abra (app .env files keep landing in the shared
  canonical path, so janitor discovery and env-based teardown are unchanged; per-domain
  filenames + the P2 app-domain lock prevent write conflicts) and a FRESH empty recipes/ —
  each run clones + checkouts its own recipe trees. Exported as $ABRA_DIR (honored by the
  abra CLI, verified on-host) before ANY abra call. Manual runs get manual-<pid> isolation.
- fetch_recipe(): plain clone into $ABRA_DIR/recipes/<recipe> — no shared-tree rm-rf, no lock.
  CCCI_SKIP_FETCH=1 now copies the canonically-staged clone into the per-run tree (same staging
  workflow, run reads staged state).
- abra.abra_dir()/recipe_dir(): single resolution rule ($ABRA_DIR else ~/.abra), used by
  recipe_checkout, has_lightweight_version_tags, recipe_head_commit, recipe_versions,
  generic._recipe_dir, lifecycle.prepull_images, snapshot_recipe_tests, and
  warm_reconcile._recipe_dir (which keeps the canonical default for its own systemd runs but
  follows the per-run tree when imported by promote_canonical inside a run).
- deleted: lifecycle.acquire_recipe_lock, RECIPE_LOCK_DIR, the main() call site and the
  must-lock-before-fetch ordering rule.
- tests/{ghost,discourse}/install_steps.sh: RECIPE_DIR resolves ${ABRA_DIR:-$HOME/.abra} so the
  compose.ccci.yml overlay lands in the tree the run actually deploys from (mechanical path fix
  required by per-run trees; no assertion/gate touched — see DECISIONS.md).
- .drone.yml comments updated (HOME=/root rationale now via the servers symlink).

tests/discourse/install_steps.sh

@@ -15,7 +15,9 @@ set -euo pipefail
 
 : "${CCCI_RECIPE:?missing CCCI_RECIPE}"
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-RECIPE_DIR="${HOME}/.abra/recipes/${CCCI_RECIPE}"
+# Resolve the recipe tree the way abra does: $ABRA_DIR (the per-run tree inside a CI run) else
+# the canonical ~/.abra — the overlay must land in the tree this run actually deploys from.
+RECIPE_DIR="${ABRA_DIR:-${HOME}/.abra}/recipes/${CCCI_RECIPE}"
 
 if [ ! -d "$RECIPE_DIR" ]; then
   echo "  discourse install_steps: recipe dir $RECIPE_DIR missing — cannot provide compose.ccci.yml" >&2

tests/ghost/install_steps.sh

@@ -15,7 +15,9 @@ set -euo pipefail
 
 : "${CCCI_RECIPE:?missing CCCI_RECIPE}"
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-RECIPE_DIR="${HOME}/.abra/recipes/${CCCI_RECIPE}"
+# Resolve the recipe tree the way abra does: $ABRA_DIR (the per-run tree inside a CI run) else
+# the canonical ~/.abra — the overlay must land in the tree this run actually deploys from.
+RECIPE_DIR="${ABRA_DIR:-${HOME}/.abra}/recipes/${CCCI_RECIPE}"
 
 if [ ! -d "$RECIPE_DIR" ]; then
   echo "  ghost install_steps: recipe dir $RECIPE_DIR missing — cannot provide compose.ccci.yml" >&2