fix(xhttp): stop injecting scMaxEachPostBytes/scMinPostsIntervalMs defaults (#5141)

The panel seeded xhttp configs with scMaxEachPostBytes=1000000 and
scMinPostsIntervalMs=30 — xray-core''s own defaults — and emitted them
into every generated config and share link. The literal
scMinPostsIntervalMs=30 is a stable DPI fingerprint that Russia''s TSPU
keys on to block connections on mobile networks.

New configs no longer seed these values (empty schema/template defaults,
so xray-core applies its internal defaults). For configs already stored
with the old defaults, the link/subscription builders now drop values
equal to xray-core''s defaults instead of advertising them — covering
panel share links, the raw subscription, and the JSON subscription
without requiring every inbound to be re-saved. Non-default values the
user set deliberately are still emitted.

frontend/src/lib/xray/stream-wire-normalize.ts

@@ -125,6 +125,8 @@ export function normalizeXhttpForWire(
   }
 
   dropEmptyStrings(out, PLACEMENT_STRING_FIELDS);
+  // Empty tuning fields mean "use xray-core's default" — never emit them.
+  dropEmptyStrings(out, ['scMaxEachPostBytes', 'scMinPostsIntervalMs', 'scStreamUpServerSecs']);
 
   if (!hasMeaningfulHeaders(out.headers)) {
     delete out.headers;