feat(ph-ai): create notebook tool

[kappa90]

Problem

New create_notebook tool aimed at the Deep Research flow, now the artifact manager supports notebook artifacts, removed old TipTap backend notebook serializer.

Changes

• Added a generic artifact type registry that maps content classes to database types (we can now extend the manager with more artifact types), with support for visualizations and notebooks
• Created a notebook streaming system that shows notebook content as it's being generated
• Added a create_notebook tool for creating rich documents with embedded visualizations
• Added support for updating existing artifacts

How did you test this code?

Tests + locally

[kappa90]

[!WARNING] This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite. Learn more

• #42909 : 2 dependent PRs (#43062 , #43070 )
• #42697 👈 (View in Graphite)
• #42696
• #42060
• #42052 : 1 other dependent PR (#42704 )
• #42888
• master

This stack of pull requests is managed by Graphite. Learn more about stacking.

[wiz-7ad640923b[bot]]

Wiz Scan Summary

Scanner	Findings
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Sensitive Data	1
Secrets	-
IaC Misconfigurations	-
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[github-actions[bot]]

Size Change: 0 B

Total Size: 3.52 MB

ℹ️ View Unchanged

Filename	Size
frontend/dist/toolbar.js	3.52 MB

_{compressed-size-action}

[posthog-bot]

Visual regression: Storybook UI snapshots updated

Changes: 14 snapshots (6 modified, 8 added, 0 deleted)

What this means:

• Snapshots have been automatically updated to match current rendering
• Next CI run will switch to CHECK mode to verify stability
• If snapshots change again, CHECK mode will fail (indicates flapping)

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[posthog-bot]

Visual regression: Storybook UI snapshots updated

Changes: 6 snapshots (6 modified, 0 added, 0 deleted)

What this means:

• Snapshots have been automatically updated to match current rendering
• Next CI run will switch to CHECK mode to verify stability
• If snapshots change again, CHECK mode will fail (indicates flapping)

Next steps:

• Review the changes to ensure they're intentional
• Approve if changes match your expectations
• If unexpected, investigate component rendering

Review snapshot changes →

[posthog-bot]

Query snapshots: Backend query snapshots updated

Changes: 1 snapshots (1 modified, 0 added, 0 deleted)

What this means:

• Query snapshots have been automatically updated to match current output
• These changes reflect modifications to database queries or schema

Next steps:

• Review the query changes to ensure they're intentional
• If unexpected, investigate what caused the query to change

Review snapshot changes →