fix: follow-ups from the post-merge reviews of #6221, #6227, #6230 and #6239 (#6250)

* fix: follow-ups from the post-merge reviews of #6221, #6227, #6230 and #6239

Six defects the automated reviews found after those PRs merged. Each is
verified rather than taken on trust — two by experiment, the rest by
reading the merged code.

**Import restore never wrote an empty local value** (#6227). GORM builds
the assignment map from the struct passed to Assign and drops zero-valued
fields, so `Assign(model.Setting{Value: ""})` produced an empty Updates
and the imported row survived. Empty is the normal state: UpdateAllSetting
writes a row for every AllSetting field including the blank ones. That is
exactly the case the PR existed for — a destination with no certificate
inheriting the source machine's path. Confirmed with a throwaway test
before changing anything: the value stayed "IMPORTED". Now uses
saveSetting, which is not zero-filtered.

**Import destroyed node mTLS material** (#6227). The "no local row means
the default applied, so drop the import" branch fires for the five
nodeMtls* keys, which are minted on demand and deliberately absent from
AllSetting, so a fresh install has no row for them. Reinstall-then-restore
therefore deleted the CA certificate and its private key — and the backup
was the only copy, since neither is surfaced in the UI or the export.
Those keys are now kept.

**The clients-list enable toggle wiped renewal state** (#6239, #6238).
setEnable hand-builds the update payload and carried reset but not
resetDay or resetMax, so one click on the switch turned calendar mode off
and lifted the renewal cap permanently. The form-modal tests could not
catch it because that path does send both fields.

**"Delete depleted clients" deleted calendar clients** (#6239). The
predicate read `reset = 0` as "does not auto-renew", which is exactly the
calendar shape, in two places. Both now share one constant that also
requires `reset_day = 0`.

**Allowlist validation and parsing disagreed** (#6230). Save used net,
scan used netip, and they differ: `198.51.100.0/024` saves without
complaint and is silently dropped at scan — the failure the PR set out to
remove. Verified by running both parsers. An IPv4-mapped prefix parsed but
could never match, because contains() unmaps the query while the prefix
stayed 128-bit; it is unmapped at parse now. A test asserts the two
acceptance sets agree.

**A comment stated the opposite of the truth** (#6221). GetInbounds has no
enable filter, so a node reports a disabled inbound normally; the row in
that bug report was missing only because it was never delivered. Reworded
to the real invariant.

Also trims two comment blocks in ip_limit_allowlist.go to the repo's
two-line maximum.

Not included: the reviewer's suggestion to lift the node hand-off out of
`if inbound.Enable` in AddInbound. It is the right root-cause fix, but it
changes delivery behaviour on multi-node deployments and belongs in its
own change with its own testing, not in a cleanup batch.

One reported finding is not real: BulkCreate does call
validateClientResetDay, validateClientResetMax and
validateClientTrafficReset — verified in the merged tree.

* fix(netsafe): wrap both errors so errorlint passes

Unrelated to this PR's subject and in a file it does not otherwise touch.
It is here only because CI lints the merge result, and `main` has been red
since #6242 landed: `fmt.Errorf("%w; %v", ...)` wraps the first error and
formats the second, which errorlint rejects. Go 1.20 allows more than one
%w, so both are wrapped now and `errors.Is` works against either.

internal/web/job/ip_limit_allowlist.go

@@ -5,19 +5,15 @@ import (
 	"strings"
 )
 
-// ipLimitAllowlist holds the operator's trusted addresses and networks. An IP
-// that matches is neither counted towards a client's IP limit nor banned:
-// counting it would still cut the office or campus NAT the entry exists to
-// protect, which is the whole point of the setting (#5378).
+// An address that matches is neither counted towards a client's IP limit nor
+// banned: counting it would still cut the shared network it protects (#5378).
 type ipLimitAllowlist struct {
 	prefixes []netip.Prefix
 	addrs    []netip.Addr
 }
 
-// parseIpLimitAllowlist reads the comma-separated form the settings validator
-// enforces, each entry either a CIDR or a bare address. Entries that do not
-// parse are skipped rather than failing the scan: the validator rejects them on
-// save, so anything reaching here is either valid or a hand-edited database.
+// Comma-separated, each entry a CIDR or a bare address. Unparseable entries are
+// skipped: the validator uses these same rules, so only a hand-edited DB differs.
 func parseIpLimitAllowlist(raw string) ipLimitAllowlist {
 	var list ipLimitAllowlist
 	for _, field := range strings.Split(raw, ",") {
@@ -26,6 +22,13 @@ func parseIpLimitAllowlist(raw string) ipLimitAllowlist {
 			continue
 		}
 		if prefix, err := netip.ParsePrefix(field); err == nil {
+			// Unmapped: contains() unmaps the queried address, and Prefix.Contains
+			// is false whenever the bit lengths disagree.
+			if addr := prefix.Addr(); addr.Is4In6() {
+				if p4, perr := addr.Unmap().Prefix(prefix.Bits() - 96); perr == nil {
+					prefix = p4
+				}
+			}
 			list.prefixes = append(list.prefixes, prefix.Masked())
 			continue
 		}

internal/web/job/ip_limit_allowlist_agreement_test.go

@@ -0,0 +1,36 @@
+package job
+
+import (
+	"testing"
+
+	"github.com/mhsanaei/3x-ui/v3/internal/web/entity"
+)
+
+// Save-time validation and scan-time parsing must accept exactly the same set:
+// anything the validator lets through and the parser drops is silently unprotected.
+func TestAllowlistValidatorAndParserAgree(t *testing.T) {
+	for _, entry := range []string{
+		"198.51.100.7",
+		"198.51.100.0/24",
+		"2001:db8::1",
+		"2001:db8::/32",
+		"198.51.100.0/024",
+		"not-an-address",
+		"198.51.100.0/33",
+	} {
+		accepted := entity.CheckNetipAddrOrPrefixList(entry, "invalid:") == nil
+		parsed := len(parseIpLimitAllowlist(entry).prefixes)+len(parseIpLimitAllowlist(entry).addrs) > 0
+		if accepted != parsed {
+			t.Errorf("%q: validator=%v parser=%v — a disagreement leaves the entry silently unprotected", entry, accepted, parsed)
+		}
+	}
+}
+
+// An IPv4-mapped prefix used to parse but never match, because contains() unmaps
+// the queried address and Prefix.Contains is false across bit lengths.
+func TestAllowlistMatchesIPv4MappedPrefix(t *testing.T) {
+	list := parseIpLimitAllowlist("::ffff:198.51.100.0/120")
+	if !list.contains("198.51.100.5") {
+		t.Fatal("an IPv4-mapped entry matched nothing: it protects no one")
+	}
+}