refactor: move analysis admin commands into psysonic-analysis (M6/7)

Reframed M6 from "extract psysonic-commands" to "place each domain's
Tauri commands in its own domain crate" — the original psysonic-commands
proposal would have been a thin shell with no clear domain ownership
because each prior milestone already kept its own commands inline:

  audio_*_commands           in psysonic-audio
  cache/sync commands        in psysonic-syncfs
  navidrome/discord/etc      in psysonic-integration

The leftover analysis admin commands (7 of them) logically belong to
the analysis domain. So they move there:

  src/lib_commands/app_api/analysis.rs   →
    crates/psysonic-analysis/src/commands.rs

  WaveformCachePayload + LoudnessCachePayload  moved out of top-crate
                                               lib.rs into commands.rs

PlaybackQueryHandle gets a second closure (`should_defer_backfill`) so
analysis_enqueue_seed_from_url can ask "is a ranged playback already
going to seed this track?" without depending on psysonic-audio.

Top crate keeps the shell-flavored commands (window/tray/mini-player,
greet/exit_app, mpris/global-shortcuts/check_dir_accessible, perf,
cli_bridge) for M7 to clean up.

Behaviour preserving. Cargo check + clippy --workspace clean.

src-tauri/crates/psysonic-analysis/src/lib.rs

@@ -7,6 +7,7 @@
 
 pub mod analysis_cache;
 pub mod analysis_runtime;
+pub mod commands;
 
 // Re-export logging facade so submodules can write `crate::app_eprintln!()`
 // the same way they did when they lived in the top crate.