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>

README.txt

@@ -4,7 +4,7 @@ Tags: woocommerce, discount, email, shipping, coupon
 Requires at least: 5.8
 Tested up to: 7.1
 Requires PHP: 7.4
-Stable tag: 1.4.5
+Stable tag: 1.4.6
 WC requires at least: 6.0
 WC tested up to: 11.1.0
 License: GPLv2 or later
@@ -96,6 +96,9 @@ The most specific match wins: exact email, then domain, then partial match.
 
 == Changelog ==
 
+= 1.4.6 =
+* Housekeeping: the plugin's source moved to a shorter address. Updates continue to arrive as before, and nothing needs doing.
+
 = 1.4.5 =
 * Fixed: the plugin could offer its own release as an update to a different plugin. Plugins that update from the same place share one check inside WordPress, and this one answered for all of them instead of only for itself. If another such plugin is installed, update it as well.
 * "Vis detaljer" next to the update notice now opens the plugin's own details, with the release notes as the changelog. It previously showed "Plugin not found", because WordPress was asking wordpress.org about a plugin that is not published there.