[Flutter hybrid support] Add slotId support to Full/Incremental snapshot records

[jonathanmos]

What does this PR do?

Extends the slotId field (already present on MetaRecord/FocusRecord) to MobileFullSnapshotRecord and MobileIncrementalSnapshotRecord, so full and incremental snapshot records can also be tagged with a slot identifier.

Motivation

Groundwork for correlating Session Replay records produced by an embedded rendering engine (e.g. Flutter) back to their placeholder slot on the native side.

Additional Notes

• slotId is optional and defaults to null; when null it's omitted from serialization (slotId?.let { ... } in generated toJson()), so existing record payloads are byte-for-byte unchanged.
• Public constructor signature for both record types changes (slotId inserted between timestamp and data) — same precedent already shipped for MetaRecord/FocusRecord, not a new risk category.
• No behavioral change to any existing recorder flow; verified full test suite passes in isolation.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[Copilot]

Pull request overview

This PR extends the existing optional slotId tagging capability (already used by MetaRecord/FocusRecord) to MobileFullSnapshotRecord and MobileIncrementalSnapshotRecord, enabling Session Replay snapshot records to be correlated back to a native “slot” (e.g., for embedded engines like Flutter).

Changes:

• Updated the JSON schemas for full/incremental snapshot records to inherit from the slot-aware common record schema.
• Updated internal record creation and test forgeries to use the new constructor shape (with slotId defaulting to null).
• Updated the Session Replay module API surface files to reflect the public model change.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
features/dd-sdk-android-session-replay/src/test/kotlin/com/datadog/android/sessionreplay/forge/IncrementalSnapshotRecordForgeryFactory.kt	Generates incremental snapshot records including optional slotId for tests.
features/dd-sdk-android-session-replay/src/test/kotlin/com/datadog/android/sessionreplay/forge/FullSnapshotRecordForgeryFactory.kt	Generates full snapshot records including optional slotId for tests.
features/dd-sdk-android-session-replay/src/main/kotlin/com/datadog/android/sessionreplay/internal/processor/RecordedDataProcessor.kt	Constructs snapshot records using named args so slotId can safely default to null.
features/dd-sdk-android-session-replay/src/main/json/schemas/session-replay/mobile/incremental-snapshot-record-schema.json	Switches base schema to _slot-supported-common-record-schema.json to add slotId.
features/dd-sdk-android-session-replay/src/main/json/schemas/session-replay/mobile/full-snapshot-record-schema.json	Switches base schema to _slot-supported-common-record-schema.json to add slotId.
features/dd-sdk-android-session-replay/api/dd-sdk-android-session-replay.api	Updates API dump to include the new constructor/copy/component signatures and getSlotId().
features/dd-sdk-android-session-replay/api/apiSurface	Updates checked-in API surface to include slotId: String? = null in both snapshot record constructors.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.24%. Comparing base (b78b347) to head (4e24dbf).
⚠️ Report is 30 commits behind head on feature/flutter-support.

Additional details and impacted files

@@                     Coverage Diff                     @@
##           feature/flutter-support    #3674      +/-   ##
===========================================================
- Coverage                    73.31%   73.24%   -0.07%     
===========================================================
  Files                          995      995              
  Lines                        36312    36305       -7     
  Branches                      6134     6136       +2     
===========================================================
- Hits                         26622    26591      -31     
- Misses                        7983     8002      +19     
- Partials                      1707     1712       +5     

Files with missing lines	Coverage Δ
...replay/internal/processor/RecordedDataProcessor.kt	97.73% <100.00%> (ø)

... and 36 files with indirect coverage changes

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