feat(sub): leastLoad member weights for subscription balancers (#6304)

* feat(model): add MemberWeights to SubBalancer

Per-inbound leastLoad weights, stored with the same gorm json serializer
as InboundIds so AutoMigrate adds the text column on every dialect
(postgresModelSettled sees the missing column and re-runs). Absent
entries mean weight 1.0; only meaningful for strategy leastLoad.

* feat(sub): accept memberWeights on the sub-balancer API

Parsed as one JSON form field (gin cannot bind bracket-keyed maps from
urlencoded bodies). validate() rejects weights under any strategy but
leastLoad — xray would silently ignore costs there, so storing them
would pretend a knob exists. Non-positive weights error instead of
defaulting: a zero usually means a typo'd "never pick this node".
Entries for inbounds no longer selected are dropped on save.

* feat(sub): emit leastLoad strategy costs from member weights

costs[] is built after the tagging loop reuses the exact retagged tags
(bal-N-protocol[-k]) and each member's owning inbound id. Members
without a configured weight default to 1.0, but costs are omitted
entirely unless at least one explicit weight survives — an all-1.0
array would bloat every subscription response for no effect.

* feat(sub-balancers): leastLoad member weight inputs

Weight fields render only under leastLoad and hide on strategy change
without dropping their values, so an accidental toggle away and back
loses nothing until save; non-leastLoad submits strip them entirely
because xray would ignore costs. Weights travel as one JSON form field
(gin cannot bind bracket-keyed maps) and every locale gets the three
new keys in the same commit per the dead-keys rule.

* docs(api): document memberWeights on sub-balancers

leastLoad-only JSON form field; update notes that omitting it clears
stored weights. Regenerated openapi artifacts via make gen + the docs
copy/gen:api step nothing checks automatically.

* fix(api-docs): use the allowed object ParamType for memberWeights

* fix(sub-balancers): cap the member-weight list height

Many selected inbounds pushed the modal body past the viewport. The
weight rows now scroll inside a 220px viewport, mirroring the inbound
picker's listHeight so both lists read the same.

* fix(sub): anchor leastLoad cost matches to exact member tags

Verified against xray-core: without regexp, WeightManager matches costs
by substring (strings.Index), so the bare tag "bal-1-vless" also hits
the deduplicated "bal-1-vless-2" and both members get the first
entry's weight. Anchored ^tag$ regexps make every cost entry match only
its own member. Also confirmed value<=0 makes xray derive a weight from
the first digit of the matched tag — validating weights > 0 server-side
was the right call.

* fix(sub-balancers): keep member weights across the enabled toggle

The table's toggleEnabled re-posted a full-row payload without
memberWeights, and the update path treats an absent key as "erase" —
flipping the switch silently dropped every configured weight. Round-trip
the stored weights through the toggle payload, and prove persistence
with a re-Get in the weight-validation test (the returned struct alone
would stay green even if Save skipped the column).

* fix(sub-balancers): address review on member weights

- omitempty on MemberWeights: the panel sends null for every pre-existing
  and non-leastLoad balancer, which failed the hand-written zod response
  schema on every fetch (zod .optional() accepts undefined only; switched
  to .nullish() per repo convention) and drifted the generated contract.
  Regenerated openapi artifacts + docs copy + MDX.
- Bound weights to the positive float32 range: xray decodes costs as
  float32, so an over-range value makes clients reject the whole
  subscription document and an underflow decays to the tag-digit
  fallback weight. Tests for both directions.
- Trim six comment blocks to the 2-line cap from CLAUDE.md.

---------

Co-authored-by: DIMFLIX <dimflix@users.noreply.github.com>

frontend/src/api/queries/useSubBalancerMutations.ts

@@ -4,15 +4,23 @@ import { HttpUtil } from '@/utils';
 import { keys } from '@/api/queryKeys';
 import type { SubBalancerFormValues } from '@/schemas/subBalancer';
 
-// Deliberately urlencoded (no JSON headers): the Go side binds inboundIds from
-// repeated form keys, which is exactly how HttpUtil encodes arrays.
+// Deliberately urlencoded: Go binds inboundIds from repeated form keys; weights
+// go as one JSON string — gin cannot bind bracket-keyed maps from form bodies.
+function toWirePayload(values: SubBalancerFormValues): Record<string, unknown> {
+  const { memberWeights, ...rest } = values;
+  if (values.strategy === 'leastLoad' && memberWeights && Object.keys(memberWeights).length > 0) {
+    return { ...rest, memberWeights: JSON.stringify(memberWeights) };
+  }
+  return rest;
+}
+
 export function useSubBalancerMutations() {
   const queryClient = useQueryClient();
   const invalidate = () => queryClient.invalidateQueries({ queryKey: keys.subBalancers.root() });
 
   const createMut = useMutation({
     mutationFn: (payload: SubBalancerFormValues) =>
-      HttpUtil.post('/panel/api/sub-balancers', payload),
+      HttpUtil.post('/panel/api/sub-balancers', toWirePayload(payload)),
     onSuccess: (msg) => {
       if (msg?.success) invalidate();
     },
@@ -20,7 +28,7 @@ export function useSubBalancerMutations() {
 
   const updateMut = useMutation({
     mutationFn: ({ id, payload }: { id: number; payload: SubBalancerFormValues }) =>
-      HttpUtil.post(`/panel/api/sub-balancers/${id}`, payload),
+      HttpUtil.post(`/panel/api/sub-balancers/${id}`, toWirePayload(payload)),
     onSuccess: (msg) => {
       if (msg?.success) invalidate();
     },