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>

teardown_all.sh

@@ -105,8 +105,12 @@ for entry in "${TEARDOWNS[@]}"; do
   log_info ">>> Tearing down Phase ${phase_num}..."
 
   if [[ "$AUTO_YES" == "true" ]]; then
-    # Pipe 'y' to all prompts in the teardown script
-    if echo "y" | "${SCRIPT_DIR}/${script}"; then
+    # Feed unlimited 'y' responses via process substitution.
+    # A pipeline (yes | script) would break under pipefail: when the script
+    # finishes and closes stdin, `yes` gets SIGPIPE (exit 141), making the
+    # pipeline report failure even though the teardown succeeded.
+    # Process substitution avoids this — only the script's exit code matters.
+    if "${SCRIPT_DIR}/${script}" < <(yes); then
       PASS=$((PASS + 1))
     else
       log_warn "Phase ${phase_num} teardown had issues (continuing)"