Add universal compute-synergy optimization doctrine

[iteathen]

Promotes the reusable optimization principles established during the Connect4 frontier-hot-loop work into the account-global agent authority.

Key additions:

• prefer invariant-bearing representations that remove work on producer and consumer sides;
• distinguish integral complexity from scope complexity;
• budget memory and compute jointly, including deliberate preallocation for fewer probes/growth/rehash/dependent loads;
• co-design identity, extraction, equality, addressing and table geometry;
• treat tiny hot-loop savings as material when invocation multiplicity justifies it;
• require system-level causal audit and paired retest for regressors before stacking;
• promote consumer-neutral native/accelerated primitives into reusable lower-layer libraries instead of embedding one-off consumer escape hatches.

This PR changes engineering guidance only; no product source or repository-local semantic contract is changed.