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.

Makefile

@@ -11,6 +11,10 @@ endif
 # Override with: CONTAINER_RUNTIME=podman make rebuild-app
 CONTAINER_RUNTIME ?= $(shell command -v docker 2>/dev/null || command -v podman 2>/dev/null)
 
+# Build stamp (stale-container drift guard): the rebuilt image carries
+# the source commit; the app logs it at boot and /api/health reports it.
+GIT_COMMIT ?= $(shell git rev-parse --short HEAD 2>/dev/null || echo none)
+
 # Dev compose stack: base prod file merged with the dev override (local build + tests).
 # Prod deploy does NOT use this — it runs plain `docker compose` against the base file only.
 COMPOSE := $(CONTAINER_RUNTIME) compose -f docker-compose.yml -f docker-compose.dev.yml