Reorder architecture sidebar using weights: stages first, then foundation, epistemology, design, implications, reference

- Add :WEIGHT: extraction to build script (from Org PROPERTIES into Hugo TOML frontmatter)
- Shorten architecture _index.org staged progression to a single-line summary pointing to stages/ directory
- Weight order (sidebar now reads in this order):
  stages/ (10-20) — the roadmap, early so references make sense
  lisp-foundation.org (21) — why Lisp
  knowledge-layers/ (30-32) — how the system knows
  design-decisions through neuro-comparison (40-45) — design
  systemic-effects (50) — implications
  org-knowledge-base through repo-organization (60-64) — reference
- Rebuild: 148 files, 0 errors

projects/passepartout/architecture/lisp-foundation.org

@@ -1,5 +1,6 @@
 :PROPERTIES:
 :CREATED:  [2026-06-03 Tue]
+:WEIGHT:  21
 :ID:       971cd9e7-2cc5-4743-8042-2469dbe4078f
 :END:
 #+title: Lisp Foundation