docs(arch): realism leads the quality list; performance moves to the end

Owner decision: prioritise realism, keep the performance target but put it last.
Re-applied on a branch after the first attempt landed directly on main (reverted
there; see b8209ce).

- Quality goals (01 + combined architecture.md): 1 visual realism, 2 geographic
  fidelity, 3 walkability/usability, 4 reproducibility/portability, 5 provenance,
  6 performance efficiency.
- Quality requirements (10 + combined) reordered to match, with two realism
  requirements added (a façade reads like the photographs; placement within ~1 m)
  and the scenarios renumbered so QS-1 is the reference comparison, QS-9 the frame
  rate.
- Guard on both documents so the order cannot become an excuse: performance is a
  floor, not a preference - 60 FPS at 1440p without frame generation must be met at
  every release; if realism cannot fit, cut the realism scope deliberately and
  record it, never the frame rate. Walkability outranks realism in one direction: a
  block you fall through is not a demo.
- Solution strategy and 'quality achievement' lead with realism and describe
  performance as a budget, not a driver.
- Docs/release-checks.md: the performance check is the last section and the per-
  version check list now opens with realism and closes with performance.
- ROADMAP gains a 'Quality priority' section; AGENTS.md gains the tie-break rule
  beside the existing scope-cutting rule.

Docs/Architecture/04_solution_strategy.md

@@ -30,7 +30,8 @@ All modelling and geographic processing live outside the game project in `Art/`,
 
 ## Quality achievement
 
-- **Performance**: dynamic-only lighting (no build step, no static shadow maps), world-space-noise materials (cheap procedural variation), minimal overdraw (simple street-level geometry).
+- **Realism first**: reference photography and measured data drive every façade decision; renders are compared against the photographs with `Tools/visual_loop.py`, and a façade is built from the shared 4.96 m module kit so the street wall reads consistently. Materials are authored in Unreal with world-aligned generated textures, and lighting is fixed daytime so a shot is comparable between runs.
+- **Performance as a budget, not a driver**: dynamic-only lighting (no build step, no static shadow maps), world-space-noise materials (cheap procedural variation), minimal overdraw for street-level geometry, and a 60 FPS at 1440p floor that every release must meet. It closes the quality list because it constrains how much realism fits, not what the block should look like.
 
 - **Walkability**: complex-as-simple collision on terrain (C++ helper forces the flag on the asset), block-all collision on every site mesh, swept transect QA verifies zero raycast holes.