feat(ph-ai): read artifacts data

[kappa90]

Problem

This PR gives the agent the ability to read again all artifacts that have been generated in the conversation, or

Changes

• Added a new aget_subagent_artifacts method to the ArtifactManager class to retrieve artifacts generated by subagents
• Extended the ReadDataTool to support retrieving artifacts with a new artifacts kind

How did you test this code?

Locally + tests incoming

[kappa90]

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

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[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 →

[graphite-app[bot]]

Merge activity

• Dec 12, 5:36 PM UTC: This pull request can not be added to the Graphite merge queue. Please try rebasing and resubmitting to merge when ready.
• Dec 12, 5:36 PM UTC: Graphite disabled "merge when ready" on this PR due to: a merge conflict with the target branch; resolve the conflict and try again..