v0.7.5 — WordPress.org slug rename: a-radio → rangerhq-radio

A third-party AI-driven naming check flagged `a-radio` as too
generic for the wp.org Plugin Directory (single common functional
word, no distinguishing prefix). The verdict was advisory but
defensible — short generic slugs are increasingly rejected as the
directory grows past 60K plugins. Fixing it preemptively is cheaper
than facing a rejection at submission time.

The new slug `rangerhq-radio` matches the public display name
"RangerHQ Radio" (unchanged) and lines up with the rest of the
RangerHQ plugin family: `rangerhq-spatial`, `rangerhq-glyph`,
now `rangerhq-radio`.

Changes (packaging only — no player behaviour change):
* Text Domain `a-radio` → `rangerhq-radio` across all 125 i18n
  call sites via in-place sed (esc_html__, _e, __, esc_attr_e
  and their friends). PHP lint clean post-rename.
* `Text Domain:` plugin header in radio.php line 15 → `rangerhq-radio`.
* `RADIO_GITEA_URL` constant value → new Gitea repo URL.
* README.md install link → new repo URL.
* readme.txt FAQ Gitea link → new repo URL.
* readme.txt Stable tag → 0.7.5.
* inc/about.php — v0.7.5 in "latest" slot; v0.7.4 demoted.

Unchanged deliberately (would have been pure churn):
* Plugin Name header "RangerHQ Radio" — already correct.
* Plugin URI.
* Internal constants `RADIO_*` — don't have to match slug.
* User-meta keys `radio_state` / `radio_history` /
  `radio_favourites` — renaming would orphan every existing
  user's settings on upgrade.
* HTML `data-radio-*` attributes — JS controller's element
  selectors in radio.js, not slug-related.
* CSS class names `radio-player`, `radio-about-*` — internal
  scoping.
* Main plugin file name `radio.php`.

Migration: existing Gitea-installed copies need their folder
renamed on disk (a-radio → rangerhq-radio) + reactivation in
WP admin. No data loss because all user-facing state lives in
user_meta under unchanged keys.

This commit is the file content for v0.7.5; the annotated tag
and push will follow the Gitea repo rename (ranger/a-radio →
ranger/rangerhq-radio) so the new tag lives in the new URL
space from the start.

README.md

@@ -12,7 +12,7 @@ A small, focused, free WordPress plugin that drops a SomaFM radio player into yo
 
 ## Installation
 
-1. Download the latest release `.zip` from [git.davidtkeane.com/ranger/a-radio/releases](https://git.davidtkeane.com/ranger/a-radio/releases)
+1. Download the latest release `.zip` from [git.davidtkeane.com/ranger/rangerhq-radio/releases](https://git.davidtkeane.com/ranger/rangerhq-radio/releases)
 2. WP Admin → Plugins → Add New → Upload Plugin
 3. Activate
 4. Look at **WP Admin → Dashboard** for the mini-player, or **WP Admin → Radio**