feat(patches): add Qwen3.6 PCP v2 (self-contained v5.2 patch set)

Adds vllm_fl/patches/qwen36_pcp_v2.py: a self-contained Qwen3.6 hybrid
(GDN) + Prefill Context Parallel patch set (v5.2). Unlike the step-1
all-gather qwen36_pcp.py, it inlines the parallel two-pass GDN op,
Path B model-runner integration, install hooks, and conv halo, with no
sibling-module imports.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: 2 people