feat: restructure technique page — bibliography key moments, ToC-only sidebar, sticky title bar, solid featured border

- Move key moments below prose as bibliography-style sources with [N] indices
- Move signal chains and related techniques to main column below key moments
- Sidebar now dedicated to ToC only, sticky with scroll tracking
- Replace position:fixed reading header with sticky title bar within content area
- ToC smooth-scrolls on click with history.replaceState for hash updates
- Featured technique card: solid cyan-to-purple gradient border (border-image)
- Remove ReadingHeader component (replaced by title bar)
- Hide sidebar ToC on mobile (single-column reading)
- Related techniques grid defaults to 2-column in main content area

.gsd/STATE.md

@@ -0,0 +1,33 @@
+# GSD State
+
+**Active Milestone:** M016: M016:
+**Active Slice:** None
+**Phase:** complete
+**Requirements Status:** 0 active · 0 validated · 0 deferred · 0 out of scope
+
+## Milestone Registry
+- ✅ **M001:** Chrysopedia Foundation - Infrastructure, Pipeline Core, and Skeleton UI
+- ✅ **M002:** M002:
+- ✅ **M003:** M003:
+- ✅ **M004:** M004:
+- ✅ **M005:** M005:
+- ✅ **M006:** M006:
+- ✅ **M007:** M007:
+- ✅ **M008:** M008:
+- ✅ **M009:** Homepage & First Impression
+- ✅ **M010:** Discovery, Navigation & Visual Identity
+- ✅ **M011:** M011:
+- ✅ **M012:** M012:
+- ✅ **M013:** M013:
+- ✅ **M014:** M014:
+- ✅ **M015:** M015:
+- ✅ **M016:** M016:
+
+## Recent Decisions
+- None recorded
+
+## Blockers
+- None
+
+## Next Action
+All milestones complete.