Go: 方法 QNs 忽略接收方 - 同一个包中的每个同名方法都会融合到一个节点上

**Status: fix open — PR #1913** (receiver-qualified Go method QNs, mirroring the C++ out-of-line block; stacked on #1907). Post-fix: `Close` methods 15 → 86 nodes, `Process` 12 → 47, `Task` 1 → 8; one generated dir recovered 1 → 63 `Close` methods (source 66; the residual 3 are #1911's twins). Generic receivers verified on real code: 45 methods across 8 generic receivers carry clean receiver-qualified QNs (`pkg.Cache.Add` for `func (c *Cache[K, V]) Add`) and zero node QNs contain a `[`. Changes extracted QNs for Go methods → reindex needed (flagged per CONTRIBUTING).