fix: pos media sync — normalize trailing-slash source + surface find errors

DOC/AGENT_Context_Project.md

@@ -602,7 +602,7 @@ Use conventional prefixes: `feat:`, `fix:`, `docs:`, `refactor:`, `chore:`
 | `bin/pos-entertainment-status` | 62 | Show enabled plugins and scheduler state |
 | `bin/pos-media-mp3` | 86 | Download audio as MP3 (yt-dlp) |
 | `bin/pos-media-mp4` | 132 | Download video as MP4 (smart/interactive format select) |
-| `bin/pos-media-sync` | 164 | Incremental Music → USB sync (mp3/mp4, add/update only) |
+| `bin/pos-media-sync` | 202 | Incremental Music → USB sync (mp3/mp4, add/update only) |
 | `bin/pos-network-checkport` | 496 | Check TCP/UDP port reachability (nmap, or bash/nc fallback) + local interface view |
 | `bin/pos-network-download` | 951 | aria2 RPC daemon + queue control (add/torrent/metalink, watch, limits) |
 | `bin/pos-network-hotspot` | 93 | Wi-Fi hotspot via create_ap + wihotspot-gui |

DOC/howto/media.md

@@ -114,7 +114,8 @@ pos media sync --mp4 --dry-run   # shows "would copy" list + counts, copies noth
 
 The source folder may be a symlink to a library elsewhere
 (`~/Music -> /mnt/data/music`) — it is followed, the artist/album tree is
-mirrored under the symlink's target.
+mirrored under the symlink's target. Symlinks *inside* the tree are not
+followed (`find -H`), and a warning reports how many were skipped.
 
 **Target picking.** Mounted USB partitions are listed with size, label and
 filesystem (single candidate → confirm prompt; several → numbered picker, one