fix(quality): clears two release/v3.8.50 base-red gates

Unblocks Merge integrity and Docs Gates for every PR against
release/v3.8.50, not just this branch:

- changelog.d/features/9415-newapi-sub2api-aggregator-balance.md had a
  non-standard YAML frontmatter header that no other fragment in the
  tree uses. check-changelog-integrity.mjs reads a fragment's first
  non-blank line to validate it starts with a markdown bullet; the
  frontmatter's leading `---` made that check fail regardless of the
  actual bullet content further down. Removed the frontmatter and
  reformatted the body to match the documented changelog.d/README.md
  bullet convention.
- docs/ops/VM_DEPLOYMENT_GUIDE.md documented OMNIROUTE_MAX_POOL_SIZE
  and OMNIROUTE_DB_POOL_SIZE as tunable env vars, but neither is read
  anywhere in the codebase (confirmed via full-repo grep) — this repo
  uses SQLite, which has no connection-pool concept these vars could
  plausibly control. check:fabricated-docs --strict correctly flags
  fabricated env-var claims; removed the bullet rather than
  implementing a feature to match invented documentation.

docs/ops/VM_DEPLOYMENT_GUIDE.md

@@ -429,6 +429,5 @@ For deployments on small VPS instances (1 GB RAM or less):
 
 - **Disable background services** — set `OMNIROUTE_DISABLE_BACKGROUND_SERVICES=1` to skip scheduler, MCP server, and periodic maintenance tasks. See `docs/reference/ENVIRONMENT.md`.
 - **Use SQLite WAL mode** — enabled by default, reduces peak memory during concurrent reads.
-- **Limit connection concurrency** — reduce `OMNIROUTE_MAX_POOL_SIZE` and `OMNIROUTE_DB_POOL_SIZE` in your environment.
 - **Avoid `next build` on the VPS** — build locally and deploy the standalone output (`.next/standalone/`).
 - **Monitor with `top` / `free -m`** — OmniRoute typically uses 200-400 MB RSS at idle on a 1 GB VM.