v2.1.0 - GMKtec community validation

Community-validation update for the Strix Halo local LLM guide.\n\nHighlights:\n- Added mottledMantis as the second major community benchmark contributor.\n- Imported GMKtec EVO-X2 96GB native Ubuntu Vulkan/RADV Qwen3.6 evidence from #16.\n- GMKtec native run reproduced the guide's Beelink Qwen3.6 UD-Q4_K_M row within -0.8% pp512 and -1.7% tg128.\n- Added GMKtec EVO-X2 WSL2/HIP baseline from #15, clearly scoped as useful Windows/WSL2 evidence rather than an apples-to-apples native Vulkan comparison.\n- Added Fail-Safe's Qwen3.6 source/build/quant follow-up from #10, including 0xSero, Unsloth UD-Q4_K_XL, and UD-Q6_K_XL rows.\n- Updated README, COMMUNITY_RESULTS.md, CONTRIBUTORS.md, SHARE.md, data/community_results.csv, and raw artifact indexes.\n- Repository validation passed on GitHub Actions for commit 7b447b7.\n\nThe live main branch remains the source of truth for ongoing community benchmark updates.