test(floating-ui): add React parity harness (#527)

* test(floating-ui): add React parity harness

* docs(floating-ui): serialize divergences

* ci(floating-ui): run browser parity with Chromium

* test(floating-ui): pin portable browser evidence

* test(floating-ui): use standards-mode browser harness

* test: split react-parity vitest projects

Follow the hook-form pattern: tag parity lanes with
testExecution group react-parity, move differential tests into a
dedicated project with globalSetup precompile, and drop per-file
beforeAll compile hooks.

* chore(ci): refresh react-parity evidence after main merge

Update lockfile and vitest.config.js integrity hashes for hook-form,
react-map-gl, and floating-ui differential lanes.

Co-authored-by: Cursor <cursoragent@cursor.com>

* chore(ci): refresh react-parity evidence after main merge

Regenerate lockfile hashes and inventory for floating-ui.

* fix(floating-ui): classify package-boundary test in parity ledger

Add the missing package-boundary.test.ts entry so react-parity:check
requires an exact 1:1 match between discovered tests and classifications.

Co-authored-by: Cursor <cursoragent@cursor.com>

* test(react-parity): expect six floating-ui classification entries

Update the binding classification unit test after adding
package-boundary.test.ts to the floating-ui parity ledger.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(ci): install Playwright for react-parity checks

Move Floating UI Chromium install from lint_checks into react_parity_checks, where react-parity:check actually runs browser lanes.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(floating-ui): keep React parity ownership package-agnostic

Point the differential lane at floating-ui-differential, narrow parity
ownership so ordinary conformance stays in shards, and move Chromium
setup into the generic harness instead of hard-coding the binding in CI.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(floating-ui): keep browser coverage ordinary, not parity-owned

Remove the octane-only Chromium positioning test from the React parity
manifest and run it through the ordinary heavy-integration browser lane
so parity ownership is reserved for React comparison evidence.

Co-authored-by: Cursor <cursoragent@cursor.com>

* test(floating-ui): execute verified upstream parity suites

* fix(ci): ignore materialized tests in marker check

* fix(floating-ui): stabilize conditional focus children

* test(floating-ui): execute pinned parity suites

* fix(ci): route Floating UI browser coverage

* fix(parity): refresh Formisch config integrity

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Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: Dominic Gannaway <trueadm@users.noreply.github.com>