Rename the repository to woo-discount-manager, keep the installed slug

Kristian named the five plugins as a family, and three repos disagreed with what
he calls them. His decision: rename the repo, never the installed slug.

MEASURED BEFORE DOING IT, because four published releases carry the old URL in
their Update URI header. A throwaway repo was created, renamed and deleted:

    old API path                    301 -> new
    old web path                    301 -> new
    old /releases/download/... path 301 -> new

and WordPress follows up to 5 redirects by default (class-wp-http.php:191), on
GET. Confirmed afterwards against the real thing: the old feed URL resolves to
v1.4.5 and the old download path still serves 48185 bytes.

So a shop on 1.4.2 keeps updating through the redirect, and 1.4.6 moves it onto
the new address directly.

PLUGIN_SLUG and PLUGIN_MAIN are deliberately untouched and now disagree with the
repository name. That is permanent: the installed directory has been
woocommerce-email-discount-manager since the first release and is on a live
shop, and changing it would not move that installation — it would put a SECOND
copy beside it and leave the old one active. ci/plugin.conf says so in the file,
because otherwise somebody will helpfully align them.

Also in, both for the family rather than for this plugin alone:

- docs/REUSE.md gains the hostname-keyed hook as a first-class section. It is
  the only bug we have found that is CAUSED by there being more than one plugin,
  so it is invisible to anyone reading a single repo — along with the same shape
  in a shared-*.php file copied into five plugins, which fatals with "Cannot
  redeclare" on the second activation without function_exists() guards.
- ci/static.sh fails on anything shaped like a credential in a tracked file.
  Suggested by the AI-manager port: a pushed key cannot be unpushed, only
  rotated. Deliberately narrow — sk-ant-, sk-, ghp_, gho_, github_pat_, AKIA,
  PRIVATE KEY blocks — because a broad entropy heuristic fires on minified
  assets and a check that cries wolf gets commented out.

Verified failing before being believed: a file containing sk-ant-api03-... makes
the step report the filename and the suite exit 1.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

ci/static.sh

@@ -143,6 +143,23 @@ for readme in readme.txt README.txt; do
     || note_fail "$readme has 'Stable tag: $stable' but the plugin header says $version."
 done
 
+ci_step "no secrets in tracked files"
+# Suggested by the AI-manager port, and it costs nothing: a pushed key cannot be
+# unpushed. It has to be rotated, and the window between the push and noticing
+# is the whole problem.
+#
+# Deliberately narrow. Broad entropy heuristics fire on minified assets, hashes
+# and base64 images, and a check that cries wolf gets commented out — which is
+# worse than not having it. These are prefixes that mean one thing only.
+before=$fails
+while IFS= read -r -d '' f; do
+  [ -f "$f" ] || continue
+  if LC_ALL=C grep -nE '(sk-ant-[A-Za-z0-9_-]{16,}|sk-[A-Za-z0-9]{32,}|ghp_[A-Za-z0-9]{30,}|gho_[A-Za-z0-9]{30,}|github_pat_[A-Za-z0-9_]{50,}|AKIA[0-9A-Z]{16}|-----BEGIN [A-Z ]*PRIVATE KEY-----)' "$f"; then
+    note_fail "$f looks like it contains a credential. It cannot be unpushed — rotate it."
+  fi
+done < <(git ls-files -z)
+[ "$fails" = "$before" ] && echo "  nothing that looks like a key or a private key"
+
 ci_step "no placeholders left in the plugin header"
 # The header is the plugin's business card: wp-admin shows the author and the
 # links to whoever installs it, so a placeholder there survives for as long as