v0.3.10 — Pure quick-select actually fixed

Pure quick-select, actually fixed this time

v0.3.9 fixed the Pure quick button by switching from MSPURE DIRECT to bare MSPURE, based on one test that appeared to show it preserving the last-active mode. A user reported it still wasn't switching categories at all -- testing from a genuinely different starting category (Movie) proved why: MSPURE is simply a no-op, not a real category-select command like MSMOVIE/MSMUSIC/MSGAME are. The earlier test was a false positive -- it happened to start from a state that command would leave unchanged either way.

The real fix

There is no telnet command for "switch to Pure, keep whatever submode was active" -- Movie/Music/Game get this natively, Pure does not. So the integration now tracks it client-side:

• coordinator.last_pure_submode remembers whichever of Direct / Pure Direct / Auto you last used.
• It updates whenever you explicitly pick one (via either Sound Mode entity), and self-heals from Direct/Pure Direct whenever the receiver reports them, from any source. (Auto can't self-heal this way -- like Movie/Music/Game, it's a resolving command itself and never reads back under its own name, so picking it explicitly is the only way the integration learns you use it.)
• The Quick select's Pure button now sends that remembered submode's own command directly, defaulting to Pure Direct only if nothing's been remembered yet.

Verified end-to-end against real hardware this time: explicitly set Direct, switched to a different category (Movie), then confirmed the Quick Pure button restores Direct -- not Pure Direct.

Upgrade

• HACS users: update -> v0.3.10 -> restart Home Assistant.
• Manual users: replace custom_components/denon_advanced_audio/ files and restart.