Remove CDS-era + EDH-probe orphan scripts and dev exploratory files

Producer migrated to EDH in v0.1.0 / #36. The R-side CDS pipeline
scripts and the EDH-evaluation probe scripts were never removed at
that time and have been carrying CDS-only references since.

Removed:
- scripts/pipeline_backfill.R, pipeline_update.R, pipeline_daily_stats_{submit,retrieve}.R,
  pipeline_e2e_test.R — pre-EDH R producer pipeline, replaced by
  scripts/backfill_edh_*.py + pipeline_stage3_edh.R + pipeline_update_edh.R
- scripts/test_edh_era5_land.py, probe_edh_vars.py — one-off #36
  evaluation probes; their job (decide on EDH) is done
- dev/peace-by-ecoregion.{Rmd,html}, dev/_peace_ecoregion_section.Rmd —
  pre-vignette exploratory drafts, superseded by vignettes/peace-fwcp.Rmd
- inst/extdata/context_kotl_towns.gpkg — untracked, no code references

Kept: R/cd_fetch.R + R/cd_derive.R + their tests — still part of
package API surface as a CDS-fallback path. Run logs in logs/*.log
also kept locally for SRED-evolution tracking; gitignored so they
stop appearing as untracked.

devtools::test() clean (166 PASS, 0 FAIL).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: NewGraphEnvironment