fix: address multiple bugs from code review

- teardown_all.sh: replace `yes |` pipeline with `< <(yes)` process
  substitution to avoid SIGPIPE (exit 141) false failures under pipefail
- phase6_teardown.sh: extract push mirror `.id` instead of `.remote_name`
  to match the DELETE /push_mirrors/{id} API contract
- phase5_migrate_pipelines.sh: expand sed regex from `[a-z_]*` to
  `[a-z_.]*` to handle nested GitHub contexts like
  `github.event.pull_request.number`
- lib/common.sh: render_template now requires explicit variable list to
  prevent envsubst from eating Nginx variables ($host, $proxy_add_...)
- backup scripts: remove MacBook relay, use direct Unraid↔Fedora SCP;
  fix dump path to write to /data/ (mounted volume) instead of /tmp/
  (container-only); add unzip -t integrity verification
- preflight.sh: add --skip-port-checks flag for resuming with
  --start-from (ports already bound by earlier phases)
- run_all.sh: update run_step to pass extra args; use --skip-port-checks
  when --start-from > 1
- post-checks (phase4/7/9): wrap API calls in helper functions with
  >/dev/null redirection instead of passing -o /dev/null as API data
- phase8: replace GitHub archiving with [MIRROR] description marking
  and disable wiki/projects/Pages (archived repos reject push mirrors)
- restore_to_primary.sh: add require_vars for Fedora SSH variables

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

preflight.sh

@@ -4,11 +4,22 @@ set -euo pipefail
 # =============================================================================
 # preflight.sh — Validate everything before running migration phases
 # Installs nothing. Exits 0 only if ALL checks pass.
+#
+# Usage:
+#   ./preflight.sh                    # Run all checks
+#   ./preflight.sh --skip-port-checks # Skip port-free checks (for --start-from)
 # =============================================================================
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 source "${SCRIPT_DIR}/lib/common.sh"
 
+SKIP_PORT_CHECKS=false
+for arg in "$@"; do
+  case "$arg" in
+    --skip-port-checks) SKIP_PORT_CHECKS=true ;;
+  esac
+done
+
 log_info "=== Preflight Checks ==="
 
 PASS_COUNT=0
@@ -204,26 +215,33 @@ fi
 # Check 13: Port free on Unraid
 # Uses ss (socket statistics) to check if any process is listening on the port.
 # The ! negates the grep — we PASS if the port is NOT found in use.
+# Skipped when --skip-port-checks is set (e.g. resuming with --start-from
+# after phases 1-2 have Gitea already running on these ports).
 # ---------------------------------------------------------------------------
-check_port_unraid() {
-  local port="${UNRAID_GITEA_PORT:-3000}"
-  ! ssh_exec UNRAID "ss -tlnp | grep -q ':${port} '" 2>/dev/null
-}
-check 13 "Port ${UNRAID_GITEA_PORT:-3000} free on Unraid" check_port_unraid
-if ! check_port_unraid 2>/dev/null; then
-  log_error "  → Port ${UNRAID_GITEA_PORT:-3000} already in use on Unraid."
-fi
+if [[ "$SKIP_PORT_CHECKS" == "true" ]]; then
+  log_info "[13] Port ${UNRAID_GITEA_PORT:-3000} free on Unraid — SKIPPED (--skip-port-checks)"
+  log_info "[14] Port ${FEDORA_GITEA_PORT:-3000} free on Fedora — SKIPPED (--skip-port-checks)"
+else
+  check_port_unraid() {
+    local port="${UNRAID_GITEA_PORT:-3000}"
+    ! ssh_exec UNRAID "ss -tlnp | grep -q ':${port} '" 2>/dev/null
+  }
+  check 13 "Port ${UNRAID_GITEA_PORT:-3000} free on Unraid" check_port_unraid
+  if ! check_port_unraid 2>/dev/null; then
+    log_error "  → Port ${UNRAID_GITEA_PORT:-3000} already in use on Unraid."
+  fi
 
-# ---------------------------------------------------------------------------
-# Check 14: Port free on Fedora
-# ---------------------------------------------------------------------------
-check_port_fedora() {
-  local port="${FEDORA_GITEA_PORT:-3000}"
-  ! ssh_exec FEDORA "ss -tlnp | grep -q ':${port} '" 2>/dev/null
-}
-check 14 "Port ${FEDORA_GITEA_PORT:-3000} free on Fedora" check_port_fedora
-if ! check_port_fedora 2>/dev/null; then
-  log_error "  → Port ${FEDORA_GITEA_PORT:-3000} already in use on Fedora."
+  # ---------------------------------------------------------------------------
+  # Check 14: Port free on Fedora
+  # ---------------------------------------------------------------------------
+  check_port_fedora() {
+    local port="${FEDORA_GITEA_PORT:-3000}"
+    ! ssh_exec FEDORA "ss -tlnp | grep -q ':${port} '" 2>/dev/null
+  }
+  check 14 "Port ${FEDORA_GITEA_PORT:-3000} free on Fedora" check_port_fedora
+  if ! check_port_fedora 2>/dev/null; then
+    log_error "  → Port ${FEDORA_GITEA_PORT:-3000} already in use on Fedora."
+  fi
 fi
 
 # ---------------------------------------------------------------------------