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/version/version.go

@@ -8,3 +8,11 @@ package version
 // The release workflow passes the git tag (e.g. v1.5) as the APP_VERSION
 // Docker build arg, which the Dockerfile forwards to this flag.
 var Version = "dev"
+
+// Commit is the git commit the binary was built from (short hash),
+// injected alongside Version via ldflags (GIT_COMMIT build arg). It
+// exists so "the UI I'm looking at" vs "the code in the repo" drift is
+// VISIBLE — the 2026-10-29 podcast debugging session burned an hour on
+// a stale container that predated the feature. "none" for unstampeded
+// local builds.
+var Commit = "none"