fix(ci): add fallback JSON extraction to issue triage workflow

[bdmorgan]

Summary

• The automated issue triage workflow has been failing since ~Feb 18 due to the model returning bare JSON instead of wrapping it in a markdown code block
• The CLI captures debug output (telemetry init, YOLO mode messages) alongside the model's JSON response, so raw JSON parsing always fails
• Previously this worked because the model consistently wrapped its JSON in json blocks, which the markdown fallback handled
• Adds a third parsing fallback that extracts a labels_to_set JSON object directly from the mixed output

Test plan

• Verify the workflow succeeds on newly opened issues
• Confirm the fix handles output with debug lines prefixed before bare JSON
• Confirm existing markdown-block and raw-JSON parsing paths still work

[gemini-code-assist]

Note

Gemini is unable to generate a summary for this pull request due to the file types involved not being currently supported.

[github-actions]

Size Change: -5.47 kB (-0.02%)

Total Size: 24.6 MB

Filename	Size	Change
./bundle/gemini.js	24.5 MB	-5.47 kB (-0.02%)

ℹ️ View Unchanged

Filename	Size
./bundle/sandbox-macos-permissive-open.sb	890 B
./bundle/sandbox-macos-permissive-proxied.sb	1.31 kB
./bundle/sandbox-macos-restrictive-open.sb	3.36 kB
./bundle/sandbox-macos-restrictive-proxied.sb	3.56 kB
./bundle/sandbox-macos-strict-open.sb	4.82 kB
./bundle/sandbox-macos-strict-proxied.sb	5.02 kB

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