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).

runner/harness/abra.py

@@ -10,6 +10,7 @@ Bakes in the known abra gotchas (re-verify per installed abra version, currently
 from __future__ import annotations
 
 import json
+import os
 import subprocess
 
 ABRA = "abra"
@@ -19,6 +20,20 @@ class AbraError(RuntimeError):
     pass
 
 
+def abra_dir() -> str:
+    """abra's state dir, resolved the same way the abra CLI resolves it: $ABRA_DIR if set, else
+    ~/.abra. Inside a CI run, run_recipe_ci exports a PER-RUN $ABRA_DIR (fresh recipes/, shared
+    servers/+catalogue/ symlinks) before any abra call, so every helper here and every abra
+    subprocess agree on the same tree; outside a run (warm_reconcile's systemd timer, manual use)
+    both fall back to the canonical /root/.abra."""
+    return os.environ.get("ABRA_DIR") or os.path.expanduser("~/.abra")
+
+
+def recipe_dir(recipe: str) -> str:
+    """The current ABRA_DIR's working tree for a recipe (per-run inside a CI run)."""
+    return os.path.join(abra_dir(), "recipes", recipe)
+
+
 def _run_pty(
     args: list[str], timeout: int = 900, check: bool = True
 ) -> subprocess.CompletedProcess:
@@ -77,9 +92,7 @@ def recipe_checkout(recipe: str, version: str) -> None:
     a chaos (`-C`) deploy ignores ENV VERSION and uses the current checkout — together that silently
     deployed LATEST for a 'previous-version' base, making the upgrade a no-op (Adversary F1d-2). With
     this checkout + a non-chaos deploy, a pinned deploy genuinely deploys that version."""
-    import os
-
-    path = os.path.expanduser(f"~/.abra/recipes/{recipe}")
+    path = recipe_dir(recipe)
     # -f (force): the version-pinning checkout must yield the EXACT ref tree. Without it, a cc-ci
     # install_steps-provided overlay (e.g. discourse's compose.ccci.yml, copied into the pinned base)
     # is an UNTRACKED file that collides with the same path TRACKED in a later ref, and
@@ -100,9 +113,7 @@ def has_lightweight_version_tags(recipe: str) -> bool:
     'reference not found'.) The caller (deploy_app) uses this to fall back to a chaos base deploy
     (which skips lint and deploys the explicitly-checked-out pinned version — see lifecycle.deploy_app).
     Read-only: just `git tag` + `cat-file -t`; no fetch/mutation, so it can't trigger abra's revert."""
-    import os
-
-    path = os.path.expanduser(f"~/.abra/recipes/{recipe}")
+    path = recipe_dir(recipe)
     tags = subprocess.run(
         ["git", "-C", path, "tag", "-l"], capture_output=True, text=True
     ).stdout.split()
@@ -231,9 +242,7 @@ def recipe_head_commit(recipe: str) -> str | None:
     """The current HEAD commit of the recipe checkout — captured right after fetch (the PR head, or
     the catalogue current) so the upgrade tier can re-checkout it for the chaos redeploy after the
     prev-tag base deploy reset the working tree (HC1)."""
-    import os
-
-    path = os.path.expanduser(f"~/.abra/recipes/{recipe}")
+    path = recipe_dir(recipe)
     proc = subprocess.run(["git", "-C", path, "rev-parse", "HEAD"], capture_output=True, text=True)
     out = proc.stdout.strip()
     return out or None
@@ -241,10 +250,7 @@ def recipe_head_commit(recipe: str) -> str | None:
 
 def recipe_versions(recipe: str) -> list[str]:
     """Published versions of a recipe, oldest→newest (from the recipe git tags)."""
-    import os
-    import subprocess
-
-    path = os.path.expanduser(f"~/.abra/recipes/{recipe}")
+    path = recipe_dir(recipe)
     proc = subprocess.run(
         ["git", "-C", path, "tag", "--sort=creatordate"], capture_output=True, text=True
     )