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>

phase4_post_check.sh

@@ -44,8 +44,10 @@ for repo in "${REPOS[@]}"; do
   log_info "--- Checking repo: ${repo} ---"
 
   # Check 1: Repo exists on primary
-  run_check "Primary: ${GITEA_ORG_NAME}/${repo} exists" \
-    gitea_api GET "/repos/${GITEA_ORG_NAME}/${repo}" -o /dev/null
+  check_repo_exists() {
+    gitea_api GET "/repos/${GITEA_ORG_NAME}/$1" >/dev/null
+  }
+  run_check "Primary: ${GITEA_ORG_NAME}/${repo} exists" check_repo_exists "$repo"
 
   # Check 2: Repo has commits (migration imported content)
   check_commits() {
@@ -67,8 +69,10 @@ for repo in "${REPOS[@]}"; do
   run_check "Primary: ${repo} default branch matches GitHub" check_default_branch "$repo"
 
   # Check 4: Mirror exists on Fedora
-  run_check "Fedora: ${GITEA_ADMIN_USER}/${repo} exists" \
-    gitea_backup_api GET "/repos/${GITEA_ADMIN_USER}/${repo}" -o /dev/null
+  check_mirror_exists() {
+    gitea_backup_api GET "/repos/${GITEA_ADMIN_USER}/$1" >/dev/null
+  }
+  run_check "Fedora: ${GITEA_ADMIN_USER}/${repo} exists" check_mirror_exists "$repo"
 
   # Check 5: Mirror has mirror=true
   check_mirror_flag() {