perf: reduce smoke-copilot token usage with pre-steps and tool trimming (#1613)

* perf: reduce smoke-copilot token usage with pre-steps and tool trimming

- Remove unused tools: agentic-workflows, cache-memory, edit, playwright, web-fetch
  (56 tools → ~10, saving ~30K tokens/request from schema overhead)
- Remove unused network groups: node, playwright
- Restrict github toolsets to [repos, pull_requests]
- Add pre-agent step to deterministically pre-compute:
  - Last 2 merged PRs via gh CLI
  - GitHub.com connectivity check via curl
  - File write/read test
- Simplify agent prompt to verify pre-computed results and format output
- Replace Playwright browser test with curl connectivity check in pre-step
- Fix safe-outputs YAML indentation (was over-indented)
- Remove sandbox.mcp.container (not allowed in strict mode)

Expected token reduction: ~60-70% per run by eliminating tool probing
turn, reducing tool schema overhead, and moving deterministic work
out of the LLM context.

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

* fix: use RUNNER_TEMP fallback for safe outputs path in post-step

The gh-aw v0.65+ compiler no longer sets GH_AW_SAFE_OUTPUTS as a
job-level env var (it uses step outputs instead). The post-step
validation was falling back to /opt/gh-aw/safeoutputs/outputs.jsonl
which doesn't exist. Use ${RUNNER_TEMP}/gh-aw/safeoutputs/outputs.jsonl
as the fallback instead.

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

* fix: inject checkout before npm ci in detection job

The post-processor's checkout injection logic was fooled by the
conditional 'Checkout repository for patch context' step in the
detection job. Since it has an 'if:' guard, it may be skipped,
leaving npm ci without a package-lock.json.

Fix the regex to skip conditional checkouts (those with an 'if:'
on the next line) so an unconditional checkout is properly injected.

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

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

Author: lpcox