chore: rename project from podpuddle to podsteadr

Renames the repo directory and every podpuddle/PODPUDDLE reference
across code, config, and docs to podsteadr/PODSTEADR (package names,
Docker Compose project/service/volume names, env var names, UI/RSS
strings). Existing Docker volume data (uploaded blobs, mediamtx
recordings, the server's sqlite DB and its nostr identity key) was
migrated to new podsteadr_-prefixed volumes with matching filenames
so it isn't orphaned by the rename.

docker-compose.yml

@@ -1,9 +1,9 @@
-name: podpuddle
+name: podsteadr
 
 services:
-  podpuddle:
+  podsteadr:
     build: .
-    container_name: podpuddle
+    container_name: podsteadr
     restart: unless-stopped
     ports:
       - "8095:8095"
@@ -21,7 +21,7 @@ services:
       BLOSSOM_URL_INTERNAL: http://blossom:3000
       NOSTR_RELAYS: ${NOSTR_RELAYS:-wss://relay.damus.io,wss://nos.lol,wss://relay.nostr.band}
     volumes:
-      - podpuddle-data:/data
+      - podsteadr-data:/data
       - mediamtx-recordings:/recordings:ro
     depends_on:
       - mediamtx
@@ -29,7 +29,7 @@ services:
 
   mediamtx:
     image: bluenviron/mediamtx:1.19.2
-    container_name: podpuddle-mediamtx
+    container_name: podsteadr-mediamtx
     restart: unless-stopped
     ports:
       - "1935:1935"        # RTMP ingest
@@ -45,7 +45,7 @@ services:
 
   blossom:
     image: ghcr.io/hzrd149/blossom-server:4
-    container_name: podpuddle-blossom
+    container_name: podsteadr-blossom
     restart: unless-stopped
     ports:
       - "8098:3000"
@@ -54,6 +54,6 @@ services:
       - blossom-data:/app/data
 
 volumes:
-  podpuddle-data:
+  podsteadr-data:
   mediamtx-recordings:
   blossom-data: