Add sync kernel readiness framework with Selenium implementation and default policies

[ajayrakde]

Motivation

• Centralize all "wait until ready" logic into a single, deterministic Sync Kernel that is intent-aware (CLICK/TYPE/NAVIGATE/ASSERT/etc.).
• Make readiness capability-driven so BiDi-dependent gates are soft/skipped when unsupported and the engine falls back to Selenium hints.
• Provide robust, facts-only diagnostics and bounded waits to avoid indefinite or heuristic-driven blocking.

Description

• Add core sync API and models: Intent, SyncKernel, WaitTarget variants, WaitOptions, WaitResult, SyncDiagnostics, and GateStatus under java/src/org/openqa/selenium/locator/sync to define the public surface.
• Introduce a policy model and defaults under sync/policy including ReadinessProfile, QuietWindows, ConsolePolicy, NetworkPolicy, StabilityPolicy, NavMode, and a DefaultSyncPolicy with intent-specific profiles and timeouts.
• Implement the Selenium-backed Sync Kernel DefaultSyncKernel and factory SeleniumSyncKernelFactory with gate evaluators, probes, and navigation-mode handling in sync/selenium/impl, including DocumentReadyGate, UrlStableGate, NetworkQuietGate, ConsoleCleanGate, GlobalAnimationsQuietGate, TargetStableGate, RouteEventSeenGate, DomTokenStableGate, JS probes (JsReadyStateProbe, JsDomTokenProbe, JsHistoryHook), and a SyncDiagnosticsBuilder for bounded diagnostics.
• Add console relevance helper, diagnostics providers, SyncTimeoutException, and applyWaitOptions/JS-fallback augmentation logic so post-action waits are stricter when JS fallbacks are used.
• Add unit tests covering gate logic and wait-loop behaviors in java/test/org/openqa/selenium/locator/sync and register them in the SmallTests suite, and add user-journey documentation (java/docs/locator-sync-user-journey.md) plus a small update to locator-engine-user-journey.md.

Testing

• Added unit tests under java/test/org/openqa/selenium/locator/sync/ and wired them into the SmallTests suite, but the full test suite was not executed in this environment.
• Attempted bazel test //java/test/org/openqa/selenium:SmallTests but the run could not complete because Bazel could not be downloaded in this environment (download forbidden), so tests were not run to completion.
• Ran rake lint as part of verification and it failed in this environment due to a missing Ruby dependency (net/telnet), so linting could not be completed here.

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Codex Task