feat(release): recursion guard for the health gate; run-task drift warning; M20 packages/* decision recorded (#39)

- release.sh health gate runs with MOSAIC_ENSURE_SKIP=1: the gated task run
  cannot re-enter release self-determination
- run-task.sh warns on release drift instead of silently using a stale image
- ROADMAP: M20 decision recorded (packages/* monorepo at usurpation,
  continuity-first); restructure sequenced as M20 phase 1

Closes #39

adapters/pi/adapter.sh

@@ -47,6 +47,19 @@ fi
 TOOLS_FLAG="--no-tools"
 [ -n "${MOSAIC_TOOLS:-}" ] && TOOLS_FLAG="--tools $MOSAIC_TOOLS"
 
+# Skills (M17): explicitly provided skill dirs replace discovery. When none
+# are provided the agent runs with --no-skills (nothing ambient to find).
+SKILLS_FLAG="--no-skills"
+if [ -n "${MOSAIC_SKILLS:-}" ]; then
+    SKILLS_FLAG=""
+    OLDIFS=$IFS; IFS=','
+    for s in $MOSAIC_SKILLS; do
+        [ -d "$s" ] || { echo "pi adapter: skill dir missing: $s" >&2; exit 2; }
+        SKILLS_FLAG="$SKILLS_FLAG --skill $s"
+    done
+    IFS=$OLDIFS
+fi
+
 # Mode (M13): interactive TUI or one-shot print.
 PRINT_MODE="-p"
 REQUEST_ARG=""
@@ -68,7 +81,7 @@ PROMPT_CONTENT="$(cat "$MOSAIC_SYSTEM_PROMPT_FILE")"
 set -- \
     --offline \
     --no-extensions \
-    --no-skills \
+    $SKILLS_FLAG \
     --no-prompt-templates \
     --no-themes \
     --no-context-files \