feat: add useAllSearchParam hook

[bosi-programming]

Adds a useAllSearchParam sensor hook that returns every URL search param as an object, so consumers don't need to instantiate useSearchParam once per param.

Closes #2390.

Changes

• src/useAllSearchParam.ts — new hook returning Record<string, string>; watches popstate/pushstate/replacestate; server fallback returns {}.
• tests/useAllSearchParam.test.ts — covers all params, empty search, updates, duplicate keys.
• src/index.ts — exports the hook.
• stories/useAllSearchParam.story.tsx, docs/useAllSearchParam.md, README.md — docs and demo.

Semantics

• Single value per key: a repeated param keeps its first value (?foo=bar&foo=baz → { foo: 'bar' }), matching useSearchParam's .get() behavior.

Verification

• yarn test — 77 suites / 496 tests pass.
• yarn lint — 0 errors.
• yarn lint:types — clean.

[bosi-programming]

Superseded by #2721 (branch renamed to pr/use-all-search-param per CONTRIBUTING.md, which closed this PR's head ref).