fix: vendor deps and fix CI go-version, timeout, GOTOOLCHAIN (HAN-414)

- Run go mod vendor to eliminate proxy.golang.org network dependency
- Set GOFLAGS=-mod=vendor at job env level so all go commands use vendor/
- Fix go-version from 1.23 to 1.24.0 to match go.mod
- Move GOTOOLCHAIN=local to job-level env (not per-step inline)
- Set cache: false on setup-go (cache is irrelevant with vendoring)
- Add timeout-minutes: 15 so failures are caught quickly instead of 3h

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: multica-agent <github@multica.ai>

vendor/github.com/miekg/dns/hash.go

@@ -0,0 +1,31 @@
+package dns
+
+import (
+	"bytes"
+	"crypto"
+	"hash"
+)
+
+// identityHash will not hash, it only buffers the data written into it and returns it as-is.
+type identityHash struct {
+	b *bytes.Buffer
+}
+
+// Implement the hash.Hash interface.
+
+func (i identityHash) Write(b []byte) (int, error) { return i.b.Write(b) }
+func (i identityHash) Size() int                   { return i.b.Len() }
+func (i identityHash) BlockSize() int              { return 1024 }
+func (i identityHash) Reset()                      { i.b.Reset() }
+func (i identityHash) Sum(b []byte) []byte         { return append(b, i.b.Bytes()...) }
+
+func hashFromAlgorithm(alg uint8) (hash.Hash, crypto.Hash, error) {
+	hashnumber, ok := AlgorithmToHash[alg]
+	if !ok {
+		return nil, 0, ErrAlg
+	}
+	if hashnumber == 0 {
+		return identityHash{b: &bytes.Buffer{}}, hashnumber, nil
+	}
+	return hashnumber.New(), hashnumber, nil
+}