Add ProHarvest Seeds: 119 varieties + 161 cross-vendor plot reports

ProHarvest Seeds (independent Corn Belt brand, proharvestseeds.com) exposes
a public, no-auth WordPress REST API — cleaner ingestion than the HTML-only
independents. Two new sources:

- `proharvest` (variety identity, 119 row-crop varieties: 70 corn / 47 soy /
  2 wheat). Enumerated via /wp/v2/seed (seed-type taxonomy), agronomics
  parsed from each /seed/<slug>/ detail page into structured
  characteristics_groups so the ratings actually embed. Mixed scale: disease
  1-9 numeric (9=best, no flip), agronomic/general qualitative, soil HR/R.

- `proharvest_plots` (trials, data_type=trial, 161 plots, 2024+2025). Per-
  cooperator harvest reports via the custom /wp-json/proharvest/v1/plots?y=
  endpoint + PDF table extraction. Many are cross-vendor head-to-head
  (ProHarvest/Apex vs Pioneer/DEKALB/Becks/Channel/Wyffels). Handles ruled
  tables, unruled tables (text fallback; soy drops the Test-Wt column → 4 vs
  5 numerics), and off-template third-party reports (sanity-gated to verbatim
  so junk rows never ship). Image-only PDFs skipped + counted.

- rag/chunk.py: route proharvest_plots through the shared cross-vendor plot
  renderer (structured) / verbatim body (raw_text fallback).
- sources.json + lessons.md (rating-scales, trial-data).
- README/CLAUDE.md corpus inventory brought current (it had drifted: bayer
  931 not 475; ebberts/lg/agrigold were unlisted). New totals: 1,645 variety
  + 6,787 trial records.

robots.txt permissive (only search + /dealer-* disallowed); no ToS
automation clause. CI rebuilds the index from the committed corpus.

corpus/proharvest_plots/phpr-corn-2025-9894.json

@@ -0,0 +1,167 @@
+{
+  "source": "proharvest_plots",
+  "source_key": "phpr-corn-2025-9894",
+  "data_type": "trial",
+  "vendor": "ProHarvest Seeds",
+  "brand": "ProHarvest Seeds",
+  "crop": "corn",
+  "state": "IL",
+  "state_abbrev": "il",
+  "city": "St. George",
+  "county": "Kankakee",
+  "year": 2025,
+  "plot_id": 9894,
+  "cooperator": "SYNERGY SEEDS",
+  "latitude": 41.1921141,
+  "longitude": -87.721736,
+  "company_representative": null,
+  "planted_date": null,
+  "harvested_date": null,
+  "previous_crop": null,
+  "row_width": null,
+  "population_seeds_per_acre": null,
+  "fungicide": null,
+  "herbicide": null,
+  "insecticide": null,
+  "tillage": null,
+  "irrigation": null,
+  "results": [
+    {
+      "rank": 20,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 93.24
+      },
+      "brand": "Burrus",
+      "product": "5C11",
+      "traits": "Powercore 4 500 1795 19.7 263.8 24 $"
+    },
+    {
+      "rank": 21,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 92.68
+      },
+      "brand": "Agrigold",
+      "product": "645-71",
+      "traits": "SS 4 500 1895 21.8 271.2 17 $"
+    },
+    {
+      "rank": 22,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 86.45
+      },
+      "brand": "Merschman",
+      "product": "2512C30",
+      "traits": "Powercore 4 500 1820 20.5 264.8 22 $"
+    },
+    {
+      "rank": 23,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 86.3
+      },
+      "brand": "Dekalb",
+      "product": "114-43",
+      "traits": "VT2P 4 500 1815 20.4 264.4 23 $"
+    },
+    {
+      "rank": 24,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 84.79
+      },
+      "brand": "Agrigold",
+      "product": "642-18",
+      "traits": "SSPro 4 500 1900 22.2 270.5 18 $"
+    },
+    {
+      "rank": 25,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 77.57
+      },
+      "brand": "ProHarvest",
+      "product": "81P20",
+      "traits": "Powercore 4 500 1785 20.1 261.0 25 $"
+    },
+    {
+      "rank": 26,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 70.0
+      },
+      "brand": "Pioneer",
+      "product": "1027",
+      "traits": "AM 4 500 1785 20.4 260.1 26 $"
+    },
+    {
+      "rank": 27,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 67.07
+      },
+      "brand": "Dekalb",
+      "product": "110-10",
+      "traits": "SS 4 500 1775 20.3 258.9 27 $"
+    },
+    {
+      "rank": 28,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 62.59
+      },
+      "brand": "Agrigold",
+      "product": "636-42",
+      "traits": "SSPro 4 500 1700 18.8 252.6 29 $"
+    },
+    {
+      "rank": 29,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 51.74
+      },
+      "brand": "ProHarvest",
+      "product": "78P95",
+      "traits": "Powercore 4 500 1720 19.7 252.8 28 $"
+    },
+    {
+      "rank": 30,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 42.34
+      },
+      "brand": "Wyffels",
+      "product": "4514",
+      "traits": "Powercore 4 500 1635 18.1 245.1 32 $"
+    },
+    {
+      "rank": 31,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 39.59
+      },
+      "brand": "Wyffels",
+      "product": "5684",
+      "traits": "Powercore 4 500 1685 19.4 248.6 30 $"
+    },
+    {
+      "rank": 32,
+      "metrics": {
+        "Yield": 9.0,
+        "+/- Ave": 37.18
+      },
+      "brand": "Burrus",
+      "product": "3H48",
+      "traits": "Vorceed 4 500 1685 19.5 248.3 31 $"
+    }
+  ],
+  "n_results": 13,
+  "raw_text": false,
+  "source_urls": [
+    "https://proharvestseeds.com/wp-content/uploads/2025/10/Corn-Granger-St-George-IL.pdf"
+  ],
+  "fetched_at": "2026-06-05T00:59:34.531588+00:00",
+  "scraper_version": "0.1.0"
+}