fix(phased-execution): resume failed session on retry, surface errors, thinking/compaction indicators

- retries now resume the failed executor's session (pre/post session
  tracking replaces the broken mtime-vs-ref check)
- report recovery from the session file when the JSON stream loses its
  tail (child signaled mid-flush)
- progress.mjs: thinking indicators (◐ thinking… / ◑ thought for Ns),
  compaction (⧉ …) and provider auto-retry lines; trims trailing
  whitespace so no blank lines after LLM text; exits 1 on truncated
  stream, model error, or missing final text (pi --mode json always
  exits 0 even on errors)
- explicit ✗ ERROR lines + exit codes: 0 ok, 1 phase failed, 130/143
  interrupted (INT/TERM traps; post-pipeline check covers the case
  where bash suppresses the INT trap after a job dies from SIGINT)
- PIPESTATUS captured in a single statement (any following command
  resets it)
- skills dir: .gitignore README.md so pi's skill scanner (which honors
  .gitignore) stops warning 'description is required'

phased-execution/scripts/run-phase.sh

@@ -11,6 +11,11 @@ set -uo pipefail
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 source "$SCRIPT_DIR/lib.sh"
 
+# Make interruptions visible: state stays in .agent/phases/todo, and the
+# failed executor's session is still resumable on the next run.
+trap 'echo; echo "✗ ERROR: interrupted (SIGINT) — ${phase:-this phase} is left in $PHASE_TODO/; re-run to continue" >&2; exit 130' INT
+trap 'echo; echo "✗ ERROR: interrupted (SIGTERM) — ${phase:-this phase} is left in $PHASE_TODO/; re-run to continue" >&2; exit 143' TERM
+
 cd "$(find_root)" || die "no .agent/phases/todo found in this or parent directories (run /to-phase or /audit-create first)"
 
 phase="${1:-}"
@@ -27,4 +32,10 @@ else
 fi
 
 build_pi_args
-execute_phase "$phase"
+if execute_phase "$phase"; then
+  exit 0
+fi
+echo "✗ ERROR: phase $phase FAILED after $MAX_FIX_ATTEMPTS attempts" >&2
+echo "  reports: $PHASE_REPORTS/${phase%.md}.a*.{md,err,validate}" >&2
+echo "  resume:  re-run this script — the failed executor session is resumed automatically" >&2
+exit 1