Freeze narrative architecture contract

[xtraid]

Summary

• freeze the Pages taxonomy, additive sitemap, component template, permalink policy, and single-owner asset semantics
• bind the canonical SAT and separate search-UNSAT examples, v2 PDF outline, shared fields, and v1 compatibility boundary
• inventory all 28 current public page sources, 53 Pages assets, 12 closed schemas, and downstream migration gates

Scope

Internal planning documents only. No public page, production code, schema, generator, dependency, or final asset changes.

Validation

• make check (151 Python tests, 17 C test binaries, native and cross-engine smoke)
• renderer: 262 passed
• make pages-check
• git diff --check
• clean worktree and no generated artifacts