Address Copilot review: accept 307/308 redirects, add Herald fragment

Two fixes from Copilot's review:

  - HTTP probes now accept 307 and 308 alongside 200/301/302. Modern
    HTTP increasingly uses 307 (temporary, method-preserving) and 308
    (permanent, method-preserving) instead of 302/301; treating them
    as failures could misclassify valid upstream sites as dead. Four
    occurrences updated: probe_site, the Phase 3 main validator, the
    Phase 2b reexport probe, and the Phase 3a rescue probe.

  - Add a Herald changelog fragment under .changes/. The repo enforces
    these via .herald.yml and the existing PR template's YAML block
    isn't a substitute for a tracked file.

Author: Jimbo4350

.changes/20260428_cardano_api_fix_haddock_links.yml

@@ -0,0 +1,17 @@
+project: cardano-api
+pr: 1180
+kind:
+  - bugfix
+  - documentation
+description: |
+  Fix broken cross-package Haddock links on the hosted documentation site.
+  Links to dependency packages (cardano-ledger-*, plutus-*, cardano-base, etc.)
+  were relative paths pointing to directories that don't exist on the site,
+  resulting in 404s. A post-processing script now resolves each cross-package
+  href via a name-suffix heuristic under *.cardano.intersectmbo.org plus a
+  small fallback list of known IOG doc-site roots, and rewrites them to
+  absolute URLs. Hrefs that don't resolve become annotated unclickable spans
+  with tooltips. A follow-up GitHub Actions step opens or comments on a
+  rolling tracking issue when the script reports actionable dead links on
+  master, tagging the PR opener so the breakage lands on someone's board
+  instead of going unnoticed.

scripts/fix-haddock-links.sh

@@ -172,7 +172,7 @@ probe_site() {
   local code
   code=$(curl -sI -o /dev/null -w "%{http_code}" --connect-timeout 5 --max-time 10 \
     "${1}/${2}/doc-index.html" 2>/dev/null || echo "000")
-  [[ "$code" == "200" || "$code" == "301" || "$code" == "302" ]]
+  [[ "$code" == "200" || "$code" == "301" || "$code" == "302" || "$code" == "307" || "$code" == "308" ]]
 }
 
 resolve_url() {
@@ -433,7 +433,7 @@ if [[ $reexport_total -gt 0 ]]; then
     # shellcheck disable=SC2016
     awk -F'\t' '{print $4}' "$REEXPORT_CANDIDATES" | sort -u | \
       xargs -P 16 -I{} sh -c \
-        'code=$(curl -sI -o /dev/null -w "%{http_code}" --connect-timeout 5 --max-time 10 "{}"); if [ "$code" = "200" ] || [ "$code" = "301" ] || [ "$code" = "302" ]; then echo "{}"; fi' \
+        'code=$(curl -sI -o /dev/null -w "%{http_code}" --connect-timeout 5 --max-time 10 "{}"); if [ "$code" = "200" ] || [ "$code" = "301" ] || [ "$code" = "302" ] || [ "$code" = "307" ] || [ "$code" = "308" ]; then echo "{}"; fi' \
         > "$REEXPORT_VALID_FILE" 2>/dev/null
   fi
 
@@ -502,7 +502,7 @@ url_count=$(wc -l < "$URLS_FILE")
 if [[ $url_count -gt 0 ]]; then
   # shellcheck disable=SC2016 # single quotes intentional: expansions evaluated by inner sh -c
   xargs -P 16 -I{} sh -c \
-    'code=$(curl -sI -o /dev/null -w "%{http_code}" --connect-timeout 5 --max-time 10 "{}"); if [ "$code" != "200" ] && [ "$code" != "301" ] && [ "$code" != "302" ]; then echo "{}"; fi' \
+    'code=$(curl -sI -o /dev/null -w "%{http_code}" --connect-timeout 5 --max-time 10 "{}"); if [ "$code" != "200" ] && [ "$code" != "301" ] && [ "$code" != "302" ] && [ "$code" != "307" ] && [ "$code" != "308" ]; then echo "{}"; fi' \
     < "$URLS_FILE" > "$DEAD_URLS_FILE" 2>/dev/null
 fi
 dead_count=$(wc -l < "$DEAD_URLS_FILE" | tr -d ' ')
@@ -550,7 +550,7 @@ if [[ $dead_count -gt 0 ]]; then
     # shellcheck disable=SC2016
     awk -F'\t' '{print $2}' "$RESCUE_CANDIDATES" | sort -u | \
       xargs -P 16 -I{} sh -c \
-        'code=$(curl -sI -o /dev/null -w "%{http_code}" --connect-timeout 5 --max-time 10 "{}"); if [ "$code" = "200" ] || [ "$code" = "301" ] || [ "$code" = "302" ]; then echo "{}"; fi' \
+        'code=$(curl -sI -o /dev/null -w "%{http_code}" --connect-timeout 5 --max-time 10 "{}"); if [ "$code" = "200" ] || [ "$code" = "301" ] || [ "$code" = "302" ] || [ "$code" = "307" ] || [ "$code" = "308" ]; then echo "{}"; fi' \
         > "$RESCUE_VALID_FILE" 2>/dev/null
   fi