fix: use upload_asset instead of upload_artifact for chart image embedding in discussions

[Copilot]

Summary

Fixes broken image links in GitHub discussions (e.g. #26211).

Root Cause

Workflows like api-consumption-report.md were using upload_artifact with temporary_id to upload chart images, then embedding them in discussions as ![chart](#aw_chart_id). After the safe-output manager resolved the temporary IDs, discussions ended up with:

![GitHub API Calls Trend](https://github.com/github/gh-aw/actions/runs/123/artifacts/456)

These artifact URLs require GitHub authentication — they redirect through an authenticated flow to Azure Blob Storage. GitHub's image proxy (Camo) cannot authenticate this redirect, so <img> tags using artifact URLs always load broken.

Fix

Replace upload-artifact safe-output configuration (used for image embedding) with upload-asset in the shared workflow components. The upload_asset tool:

1. Returns the permanent URL immediately to the agent — https://github.com/repo/blob/assets/…?raw=true
2. Pushes the file to a permanent git branch (no expiry unlike 30-day artifact retention)
3. The ?raw=true URL renders as an inline image for authenticated GitHub users

The agent now receives the URL directly and embeds it literally, rather than using a #aw_temporary_id placeholder that gets swapped in later.

Changes

File	Change
shared/trending-charts-simple.md	Replace upload-artifact safe-output with upload-asset; update agent instructions
shared/python-dataviz.md	Same
api-consumption-report.md	Remove own upload-artifact config (shared import provides upload-asset); rewrite Step 5 to use upload_asset and Step 6 to use direct URLs instead of #aw_* placeholders
.github/aw/charts.md	Fix documentation examples to show upload-asset configuration
*.lock.yml	Recompiled — affected workflows now include an upload_assets job with contents: write