chore: Lowercase SvelteKit helper grid exports

[ainsleyclark]

Motivation

• Ensure the SvelteKit helper component paths are consistent by using a lower-case grid directory to match other component exports and typical import paths.

Description

• Rename the components/Grid directory to components/grid and move Container.svelte, Row.svelte, Column.svelte and index.ts into the new folder.
• Update the package entry re-exports in packages/sveltekit-helper/src/index.ts to ./components/grid/index.js.
• Update the package exports mapping in packages/sveltekit-helper/package.json to reference ./components/grid and corresponding dist paths.
• Refresh documentation and context examples to import from @ainsleydev/sveltekit-helper/components/grid and add a patch changeset at .changeset/grid-lowercase.md.

Testing

• No automated tests were run for this change.

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Codex Task

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.94%. Comparing base (7f6b060) to head (b00672d).
⚠️ Report is 494 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #408      +/-   ##
==========================================
+ Coverage   64.59%   69.94%   +5.35%     
==========================================
  Files         154      185      +31     
  Lines        6064     7394    +1330     
==========================================
+ Hits         3917     5172    +1255     
+ Misses       2064     2025      -39     
- Partials       83      197     +114     

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