⚡ pelis-agent-factory-advisor: remove unused GitHub toolset, pre-fetch docs (#1680)

* Initial plan

* feat: optimize pelis-agent-factory-advisor token usage

Agent-Logs-Url: https://github.com/github/gh-aw-firewall/sessions/1aebd4ac-a30e-49f0-a2f7-3eb570242a2d

* fix: address review feedback on docs pre-fetch

- Add set -o pipefail so curl failures are detected and emit '(not found)'
  instead of silently producing empty content
- Write pre-fetched docs to workspace file instead of $GITHUB_OUTPUT,
  since steps compile into the agent job but the prompt is rendered in
  the activation job — ${{ steps.fetch-docs.outputs.DOCS_CONTENT }}
  would always be empty
- Remove stale GH_AW_EXPR_D5B28826 env vars from activation job
- Prompt now instructs the agent to read .pelis-agent-factory-docs.txt

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Landon Cox <landon.cox@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 3 people