Fix page_engagement_views_report: correct uniqueness test grain and platform user joins

[Copilot]

page_engagement_views_report had two correctness issues: the dim_user join only matched mitxonline users, dropping all others, and the uniqueness test used unit_title which is not unique across blocks (two verticals in the same course can share the same title).

Changes

• Multi-platform user join: replaced single mitxonline_openedx_user_id join with platform-conditional OR join covering mitxonline, edxorg, mitxpro, and residential
• Block category filters: added block_category = 'sequential' to subsection_blocks CTE and block_category = 'chapter' to section_blocks CTE to avoid cross-block-type join pollution
• Removed unnecessary GROUP BY: int__combined__course_runs already has unique courserun_readable_id; the aggregation was pure overhead
• Fixed uniqueness test grain: added unit_block_id (unit_blocks.block_id) to the SELECT and switched the compound uniqueness test from unit_title to unit_block_id, which is the actual surrogate key for the block

-- Before: fails when two verticals share a title
["user_email", "courserun_readable_id", "unit_title"]

-- After: reflects true grain of the data
["user_email", "courserun_readable_id", "unit_block_id"]

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[quazi-h]

@copilot is this PR still relevant to the branch it is being merged into?

[Copilot]

@copilot is this PR still relevant to the branch it is being merged into?

No, this PR is no longer relevant. The base branch (page-engagement-views-report) already has commit 4a596719 ("Fix multiple issues in page_engagement_views_report") from @quazi-h that independently addressed the same Sentry uniqueness test bug this PR was created to fix — using block_fk (directly from the fact table) rather than a new unit_block_id column.

Additionally, merging this PR as-is would be harmful: it would delete the problem_engagement_detail_report model documentation that was added to _reporting__models.yml in commit f543d4fe.

This PR can be closed.