Clarify the task, output geometry, and method boundary

[GoGoKo699]

Summary

This bounded reviewer-support update makes the repository easier to audit without changing the core Hopf-QBP circuits or theorem.

• leads the README with the exact complete-gradient task and separates independent executions, controlled-reflection calls, logical Hopf work, Walsh decoding, and output size;
• adds a neutral method comparison organized by returned object and access model;
• adds an exact Hopf coordinate-versus-frame separation witness;
• documents sufficient raw, frame, natural-coordinate, and damped-natural norm scales;
• distinguishes the ambient-sphere phase metric used by the Hopf papers from the optional projective Fubini--Study quotient;
• clarifies that uniform phase is an objective-invariance direction, not metric-null in the adopted ambient convention;
• adds Qibo-free helpers and tests for the separation, phase metrics, support rank, and norm hierarchy;
• updates the claim map and reproducibility checklist.

Scope

The update does not add a hardware benchmark, optimizer comparison, noise model, lower bound, or new manuscript claim. The multiplexed compiler remains an exact ideal-model state-equivalent construction rather than a hardware-noise robustness claim. The norm hierarchy gives sufficient bounds for the displayed decoder, not a converse or optimality theorem.

Validation

Both GitHub Actions jobs pass on head 2bab7caab12b5248dd41e7773f07fae5a927205f:

• Qibo-free analytic validation;
• complete exact-logical Qibo validation.

The branch is based directly on current main, is nine commits ahead with no divergence, and is mergeable.