feat(nanoviews): rename effect attributes from $$name to name$

[dangreen]

Renames all effect attributes to the name$ convention, since the old name$ meaning is gone: $$autoFocus -> autoFocus$, $$checked -> checked$, $$classList -> classList$, $$files -> files$, $$ref -> ref$, $$selected -> selected$, $$style -> style$, $$value -> value$.

Also updates README, weather examples, size-limit config, and adds type tests for if_ value narrowing.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.96%. Comparing base (3d2aec6) to head (2c1a4af).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #188   +/-   ##
=======================================
  Coverage   83.96%   83.96%           
=======================================
  Files         138      138           
  Lines        2988     2988           
  Branches      564      564           
=======================================
  Hits         2509     2509           
  Misses        340      340           
  Partials      139      139           

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