Research llama.cpp runtimes + SGLang; fix AGENTS.md OKF spec link

Fan out subagents to compare mainline llama.cpp, charlie12345/ROCmFPX,
and ik_llama.cpp, then add their findings to the project knowledge base:
- docs/Research/Llama Cpp Runtimes.md  (positioning + quantization + server fit)
- docs/Research/Llama Cpp Code Diff.md (code-level quant diff, table, recommendations)
- docs/Research/SGLang.md              (what SGLang is, comparison, our-boxes fit)
- docs/Research/index.md               (Research progressive-disclosure index)
Cross-linked from docs/index.md (root) and docs/LLM/index.md.

AGENTS.md:
- Add Documentation Authoring section: docs/ is an OKF bundle; point doc authors
  at the canonical spec in the system-config knowledge base
  (~/.pi/agent/docs/references/okf-spec.md), not the orphaned
  docs/references/okf-spec.md; consolidate read-index/one-concept-per-file/
  progressive-disclosure/citation rules.
- Map AGENTS.md to docs_completeness.bats in the focused pre-commit hook (it was
  last committed before the hook existed and had no mapping).

scripts/test-changed.sh

@@ -131,6 +131,10 @@ for path in "${CHANGED[@]}"; do
         dankclaw/hermes/*)
             add_test tests/docs_completeness.bats
             ;;
+        AGENTS.md)
+            # The authoring rulebook; validate the docs vault whenever it changes.
+            add_test tests/docs_completeness.bats
+            ;;
         *)
             die "no focused-test mapping for '$path'; add one before committing"
             ;;