gh_plot_reports corpus (4,299 plots) + concurrency + 4-GPU pool

CORPUS — 4,299 GH plot reports added (3,797 written + 502 from the
earlier slow run + 319 sitemap-listed URLs that 404'd as
discontinued). Combined with prior 760 varieties + 14 AgriPro
trials = 5,073 total chunks now indexed.

scrape/sources/gh_plot_reports.py — concurrency speedup:
- 4 worker threads (ThreadPoolExecutor), each with its own
  requests.Session for connection-pool efficiency.
- Shared class-level rate limiter (0.25 sec between ANY two
  requests across all threads). Net throughput ~4 req/sec —
  well below any rate-limit threshold a public site enforces.
- Diagnosis vs original 1 req/sec: GH had ZERO rate limiting,
  zero 429s, zero retries. The 1 sec self-throttle was just too
  conservative. Bench:
    1 worker  / 1.0 sec throttle:  ~0.4 plots/sec (190 min ETA)
    4 workers / 0.25 sec throttle: ~3 plots/sec  (~25 min actual)

rag/chunk.py — chunk size cap for nomic-embed-text's 2048-token
context window:
- Empirically tested: failure threshold is ~5,250 chars on
  numeric-heavy trial chunks (chars/token ratio 2.4 vs 3.5 for
  prose). Cap at 4,500 chars to be safely under at worst-case
  2.2 chars/token.
- Applied to BOTH variety and trial chunks. Marked truncated
  chunks with metadata.embed_truncated = True; FULL text stays
  in the on-disk .md for get_page to return verbatim.

.gitea/workflows/{refresh,image-only}.yml — OLLAMA_URL pool
restructured for the 4 GPU-pinned endpoints. Bench (50-chunk
batches on nomic-embed-text):

    .0.125:11434  (RTX 40-series)  242 embeds/sec  ← weight ×4
    .0.2:11436    (GPU-pinned)     108 embeds/sec  ← weight ×2
    .0.2:11435    (GPU-pinned)      72 embeds/sec  ← weight ×1
    localhost     (TITAN X)         37 embeds/sec  ← weight ×1

Weighting is done by listing the URL multiple times in
OLLAMA_URL since the embedder uses round-robin. .0.2:11434 is
explicitly EXCLUDED — it isn't pinned to a specific GPU.

Combined index rebuild for 5,073 chunks now finishes in ~3 min
(was 19+ on the single-endpoint pool).

Smoke tests:
✓ list_versions: 5,073 docs across 6 sources, 2 vendors, 6
  brands, 4 crops (corn 2711, soy 2016, silage 223, wheat 123).
✓ search_trials({crop=corn, state=IA, year=2024}): 3 IA 2024
  corn trials surfaced.
✓ search_trials("Phytophthora resistance soybean trial"): NK
  NK43-W1XFS top-1 in LA 2024 trial (cross-vendor result).
✓ search_trials("AP Iliad Idaho wheat"): AgriPro Washington/N
  Idaho 2025 trial surfaced.
✓ search_trials(product=DKC65-95): 3 corn trials containing
  that hybrid in IL/IA 2024.
✓ search_trials(product=NK1701): 3 corn trials in AR/MS 2024.
✓ Product filter correctly returns EMPTY for products that
  aren't in the corpus (DKC65-20 is a 2023 product; 2023 plots
  deferred). Anti-hallucination contract preserved.

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

corpus/gh_plot_reports/ghpr-silage-mn-2024-2418940.md

@@ -0,0 +1,32 @@
+# Silage yield trial — Minnesota, 2024
+
+- **Source:** Golden Harvest plot report (cross-vendor head-to-head)
+- **Crop:** Silage
+- **State:** Minnesota (MN)
+- **Year:** 2024
+- **Plot ID:** 2418940
+- **Cooperator:** Chs Herman
+- **Planted:** 2024-05-14
+- **Harvested:** 2024-09-11
+- **Population:** 33,000 seeds/acre
+- **Row width:** 30"
+- **URL:** https://www.goldenharvestseeds.com/silage/plot-report/mn/2024/2418940
+
+---
+## Results (top-down by rank)
+
+| Rank | Brand | Product | Traits | Ton/Acre | Milk Per Acre | Milk Per Ton | Beef Per Acre | Beef Per Ton |
+|---|---|---|---|---|---|---|---|---|
+| 1 | NK | NK9400-V | - | 29.0 | 3618.0 | 31470.0 | 260.0 | 1993.0 |
+| 2 | Enogen | E095D3-D | - | 25.3 | 3556.0 | 26942.0 | 256.0 | 1727.0 |
+| 3 | NK | NK9231-AA | - | 24.9 | 3078.0 | 22954.0 | 184.0 | 1515.0 |
+| 4 | NK | NK9805-DV | - | 23.1 | 3149.0 | 21866.0 | 196.0 | 1438.0 |
+| 5 | NK | NK8711-V | - | 22.6 | 3572.0 | 24171.0 | 259.0 | 1549.0 |
+| 6 | NK | NK9535-V | - | 21.7 | 2906.0 | 18904.0 | 150.0 | 1267.0 |
+| 7 | NK | NK9021-D | - | 21.5 | 3322.0 | 21402.0 | 218.0 | 1381.0 |
+| 8 | Enogen | E092W5-D | - | 20.1 | 2909.0 | 17503.0 | 149.0 | 1188.0 |
+| 9 | Enogen | E094Z4-D | - | 19.7 | 3076.0 | 18166.0 | 192.0 | 1214.0 |
+| 9 | Greenfield | Genetics | 55Z93 | 19.7 | 3057.0 | 18078.0 | 199.0 | 1229.0 |
+| 11 | NK | NK9044-AA | - | 18.9 | 2800.0 | 15883.0 | 163.0 | 1112.0 |
+
+Top 5 by Ton/Acre: NK9400-V (NK) 29.0, E095D3-D (Enogen) 25.3, NK9231-AA (NK) 24.9, NK9805-DV (NK) 23.1, NK8711-V (NK) 22.6.