⚗️ Add canvas recording init configuration - #4947

Motivation

Prepare the Browser SDK configuration surface for Session Replay canvas recording while keeping the capability behind an experimental feature flag. Using an object for the canvas option leaves room for future controls such as maximum image size or compression type without adding more top-level initialization parameters.

Design references:

• One Pager: Session Replay Canvas Support
• Browser SDK Canvas Support

Changes

• Add the hidden enableSessionReplayCanvasRecording RUM initialization object.
• Add the nested maxFramesPerSecond option, defaulting to 1 FPS with a supported range from 0 to 5 FPS. Setting it to 0 disables canvas frame recording.
• Require both the canvas recording object and the session_replay_record_canvas experimental feature flag before the configuration is effective.
• Keep canvas recording disabled when the object is omitted or the experimental feature is unavailable.
• Add a reusable finite number field to the js-core configuration schema, with optional inclusive min and max bounds.
• Update the js-core API report and add focused unit coverage for defaults, custom frame rates, feature gating, and invalid option shapes.

Test instructions

• yarn test:unit --spec packages/js-core/src/entries/configuration.spec.ts --spec packages/browser-rum-core/src/domain/configuration/configuration.spec.ts
• yarn typecheck
• yarn api:check
• ESLint and Prettier checks on the changed source and test files.

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.
• Updated documentation and/or relevant AGENTS.md file