refactor(log): in-place writer lifecycle and span-based core observability (#7889)

* refactor(log): migrate logging to tracing-estuary pipeline

Swap flexi_logger + clash-verge-logger wiring for the tracing-estuary
crate: buffered file sink with explicit panic/exit drains, live level
switching, and tokio-trace/chrome-trace behind crate features.

AsyncLogger moves in-house (VecDeque ring); file format and rotation
stay unchanged.

* fix(log): reset sidecar writer in place and re-pin service-ipc v2.6.7

Rebuilding the sidecar FileLogWriter on config changes leaked flexi's
unstoppable flusher thread plus an fd each time; the writer is now flushed
and reset in place, matching what the service crate does.
get_clash_logs_by_service drops the CompactString conversion layer now that
service-ipc v2.6.7 returns plain Vec<String>, and AsyncLogger is renamed
LogRing to match.

* refactor(log): span-based observability and log noise cleanup

Instrument spans carry the structure flat lines never could: the core-start
spine (mode, readiness/owner generations, pid, config file), proxy apply and
clear routes with guard generations, service IPC sessions with refusal codes
and outcomes, profile-switch terminal outcomes, subscription fetch strategies,
core upgrades with per-proxy version probes, backup flows, timer tasks, config
generation uids, and the startup setup flow; running-mode changes emit one
guarded transition event each.
~90 hand-written noise lines are gone or demoted (entry+success pairs, polled
getter echoes, phase brackets, window sub-steps, platform install chatter);
errors keep their anyhow chain, operation name, and item id, and swallowed
retry results surface per attempt.

src-tauri/src/utils/resolve/dns.rs

@@ -27,7 +27,7 @@ pub async fn set_public_dns(dns_server: String) {
     use tauri_plugin_shell::ShellExt as _;
     let app_handle = handle::Handle::app_handle();
 
-    logging!(info, Type::Config, "try to set system dns");
+    logging!(debug, Type::Config, "try to set system dns");
     let resource_dir = match dirs::app_resources_dir() {
         Ok(dir) => dir,
         Err(e) => {
@@ -75,7 +75,7 @@ pub async fn restore_public_dns() {
     use crate::{core::handle, utils::dirs};
     use tauri_plugin_shell::ShellExt as _;
     let app_handle = handle::Handle::app_handle();
-    logging!(info, Type::Config, "try to unset system dns");
+    logging!(debug, Type::Config, "try to unset system dns");
     let resource_dir = match dirs::app_resources_dir() {
         Ok(dir) => dir,
         Err(e) => {