Refresh VRL snapshot after adding per-function stdlib labels

[pront]

Summary

• Added 194 stdlib: <function> labels to vectordotdev/vrl — one per VRL stdlib function (abs, parse_json, is_ipv4, casing functions, crypto functions, etc.), using the existing stdlib: naming convention and #aaaaaa color.
• Applied labels to 67 open issues (title-matching) and 165 PRs from the past 2 years: 88 via title match + 77 via files-touched (PR modifies src/stdlib/<fn>.rs).
• Skipped 47 cross-cutting PRs that touch >3 stdlib files (framework refactors, clippy sweeps, Rust toolchain bumps) — list available locally at /tmp/vrl_pr_files_broad.json.
• Refreshed local data via fetch-all + generate-all + plot.py (2y window). Updates issue/PR JSON snapshots, CSV summaries, and PNG charts.

One label name (stdlib: parse_aws_cloudwatch_log_subscription_message) had to be truncated to 50 chars to fit GitHub's limit — full identifier is preserved in the label description.

Test plan

• Verify chart diffs in data/images/vectordotdev_vrl_*.png look reasonable
• Spot-check a few labeled issues/PRs on GitHub
• Confirm trends/vrl.md rendered table looks right