Rename project: battlenet-manager → umutray

Binary, crate, clap app name, ksni tray id, HTTP user-agent, systemd unit,
XDG config dir (co.aleshym/umutray), README, and all log prefixes.

Config path changes from ~/.config/battlenet-manager/ to ~/.config/umutray/.
Existing users should `mv` the old directory if they've customised it;
otherwise defaults get rewritten on next run.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/diagnose.rs

@@ -58,7 +58,7 @@ pub fn run(config: &Config) {
                     if age > 300 {
                         checks.push(Check::fail(
                             "agent.lock",
-                            format!("stale lock ({age}s old) — may cause BLZBNTBNA00000005; run: battlenet-manager kill"),
+                            format!("stale lock ({age}s old) — may cause BLZBNTBNA00000005; run: umutray kill"),
                         ));
                         issues += 1;
                     } else {
@@ -108,7 +108,7 @@ pub fn run(config: &Config) {
             checks.push(Check::fail(
                 "proton",
                 format!(
-                    "{} not found — run: battlenet-manager update-proton --version={}",
+                    "{} not found — run: umutray update-proton --version={}",
                     config.proton_version, config.proton_version
                 ),
             ));