feat(podcasts+ops): Apple launcher-scheme feeds + visible build stamp

Apple scheme normalization (follow-up to the Scribl discussion): Add
Feed accepts the launcher spellings podcast pages ship next to plain
RSS — itpc://, podcasts://, feed:// — and rewrites them to the https
feed URL they wrap (scheme match case-insensitive). http stays and the
guard still rejects it. Unit-pinned.

Build stamp (stale-container drift guard): the 2026-10-29 podcast
session lost an hour to a container running a build that predated the
feature. version.Commit rides ldflags from a GIT_COMMIT build arg; the
dev compose passes git rev-parse --short HEAD via the Makefile; the
app logs 'Bookhoard <ver> (commit <hash>)' at boot and /api/health
reports it — the UI and the repo can no longer silently diverge.

internal/services/podcast_rss_test.go

@@ -290,3 +290,14 @@ func newInsecureFeedServer(t *testing.T, body string) *httptest.Server {
 	t.Cleanup(srv.Close)
 	return srv
 }
+
+// Apple Podcast launcher schemes normalize to the https feed they wrap.
+func TestNormalizeFeedURL(t *testing.T) {
+	assert.Equal(t, "https://x.test/feed.xml", normalizeFeedURL("itpc://x.test/feed.xml"))
+	assert.Equal(t, "https://x.test/feed.xml", normalizeFeedURL("podcasts://x.test/feed.xml"))
+	assert.Equal(t, "https://x.test/feed.xml", normalizeFeedURL("feed://x.test/feed.xml"))
+	assert.Equal(t, "https://x.test/feed.xml", normalizeFeedURL("ITPC://x.test/feed.xml"), "scheme match is case-insensitive")
+	assert.Equal(t, "https://x.test/feed.xml", normalizeFeedURL("https://x.test/feed.xml"))
+	assert.Equal(t, "http://x.test/feed.xml", normalizeFeedURL("http://x.test/feed.xml"), "http stays — the guard rejects it downstream")
+	assert.Equal(t, "", normalizeFeedURL("   "))
+}