Raise polyfill correctness bundle budgets

[olavoasantos]

Problem

The complete polyfill correctness stack fit within the 12 kB polyfill and 17 kB core-remote budgets before review. Addressing the final review feedback adds the state and ordering needed for scoped custom-element reactions, pending subtree hook publication, reentrant adoption, namespace-aware transport updates, and stricter selector and parser behavior.

The reconstructed integration now measures:

• @remote-dom/polyfill: 12.22 kB against the current 12 kB limit;
• @remote-dom/core (remote): 17.16 kB against the current 17 kB limit.

Keeping the existing limits would require dropping reviewed correctness behavior or performing a separate size-optimization pass before the stack can land.

Change

Raise the two affected budgets by 500 B:

• polyfill: 12 kB → 12.5 kB;
• core remote: 17 kB → 17.5 kB.

The remaining package budgets are unchanged. This PR contains no runtime code.

Validation

With the corrected integration and these limits:

• lint passes;
• type-check passes;
• build passes;
• 55 test files / 685 tests pass;
• classified WPT passes 4/4 files;
• Playwright passes after retrying four detached/unstable-element timeouts, matching the stack's previously observed retry pattern;
• bundle checks pass with 281 B of polyfill headroom and 335 B of core-remote headroom.

Ordering

Land this budget change before integrating the dependent polyfill correctness stacks. PR #692 remains parked for reconstruction on the final integrated main.