[codex] Fix p848 CI clean-checkout assumptions

[SproutSeeds]

Summary

Fix the p848 CI failures from the clean GitHub Actions checkout by removing two local-machine assumptions:

• p848 ORP/live-frontier audit scripts now fall back to tracked packet summaries when ignored orp/ or output/ artifacts are absent.
• source-index audit scripts now use in-process JS source scanning instead of requiring system rg.
• the tail-282 alignment test now checks the actual source-path existence value instead of assuming ignored live-frontier artifacts are present.

Root Cause

The April 19 main CI run failed after npm ci succeeded because the test suite expected local/generated artifacts that are intentionally ignored by git:

• orp/research/...
• output/frontier-engine-local/.../SIX_PREFIX_*_FAMILY_MENU.json

The same p848 test file also exercised scripts that shell out to rg, which is available on the development machine but not guaranteed in the GitHub Actions runner.

Impact

This blocked repo CI and skipped the CI npm pack --dry-run step. It did not appear to block normal npm installs of erdos-problems@0.3.8, but clean-checkout contributors and CI could fail on the p848 audit surface.

Validation

• node --test test/p848-282-alignment-obstruction-packet.test.js
• env PATH=/tmp/erdos-node-only-bin node --test test/p848-282-alignment-obstruction-packet.test.js
• npm test
• env PATH=/tmp/erdos-node-only-bin:/usr/bin:/bin node --test

The final full-suite no-rg run passed 238/238 tests.