bayer_seeds: add Channel + DEKALB silage/sorghum/canola + Deltapine cotton

User flagged that Channel is expanding into their area — re-walked
the cropscience.bayer.us sitemap and found 8 additional brand×crop
paths beyond the original DEKALB/Asgrow/WestBred triple. Patches
the scraper to walk all of them; total Bayer varieties roughly
doubles from 475 to 931 and the corpus picks up first-ever
coverage in sorghum (36), cotton (30), canola (6), and silage as a
distinct crop (was conflated with corn before).

Net new varieties: 456
  Channel    corn=181  soy=67   silage=54  sorghum=18    (320)
  DEKALB     silage=82 sorghum=18  canola=6              (106)
  Deltapine  cotton=30                                    (30)

scrape/sources/bayer_seeds.py
- Replace `BRANDS` (brand → 1 path) and `CROP_SUFFIX` (brand → 1
  suffix) with a flatter `BRAND_PATHS` list of (brand, url_path,
  crop, is_primary_for_brand) entries. Channel and DEKALB are now
  multi-crop brands; the same scraper walks every brand×crop pair.
- source_key derivation: for a brand's PRIMARY crop, strip the
  trailing `-<crop>` suffix (matches the existing deployed source
  keys for DEKALB corn / Asgrow soy / WestBred wheat). For
  SECONDARY crops, KEEP the suffix so DEKALB-the-same-SKU sold as
  both grain corn and silage gets two distinct source_keys
  (collision-safe and unambiguous for `lookup_variety`).
- New `--crop` CLI filter for incremental backfills.
- Log line shows brand + crop alongside source_key for visibility.

rag/chunk.py
- Channel + Deltapine pages use slightly different characteristics
  group labels (DISEASE not DISEASE RATINGS, AGRONOMIC
  CHARACTERISTICS not GROWTH/HARVEST, plus MATURITY / ADAPTATION /
  HERBICIDES / OTHER). Fold them into the DISEASE / AGRONOMIC /
  MANAGEMENT label sets so the chunker buckets them correctly
  into the standard sections.

Smoke-tested cross-brand × cross-crop queries against the rebuilt
index (5,529 chunks total) — all 6 sample queries surface the
right brand+crop at top-3:
  Channel corn 110 RM       → 210-25TRE BRAND
  Channel soy 2.5 MG IA     → 2622RXF BRAND
  Deltapine cotton XF       → DP 1820 B3XF BRAND
  Sorghum dryland Kansas    → 6B95 BRAND (Channel)
  Silage corn WI dairy      → DKC64-44RIB BRAND BLEND (silage variant)
  Canola Northern Plains    → DK401TL BRAND

Watchtower will pull the new image on the next push; deploy is
unchanged otherwise.

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

corpus/bayer_seeds/dekalb-dkc62-08-silage.md

@@ -0,0 +1,117 @@
+# DKC62-08 BRAND
+
+- **Vendor:** Bayer
+- **Brand:** Dekalb
+- **Crop:** Silage
+- **Traits:** SS (SmartStax®)
+- **Release year:** 2012
+- **Source:** https://www.cropscience.bayer.us/silage/dekalb/dekalb-dkc62-08-silage
+- **Rating scale (Bayer):** 1-9 (9 = best)
+
+---
+## Positioning
+
+DKC62-08 Brand is a 112 RM corn that offers exceptional top-end yield potential and very good agronomics. It can be adapted to most crop rotations and a wide range of environments including both irrigated and non-irrigated acres.
+
+## Strengths & management
+
+- Offensive product with exceptional top-end yield potential
+- Has shown very good stalk and root strength
+- Very good drought tolerance
+- Very good drydown and test weight
+- Can perform best when planted at M-H plant populations
+- Adapted to most crop rotations including corn on corn
+- Responds well to irrigation
+- Use caution when applying growth regulator herbicides
+- Avoid using ALS herbicides
+
+## Management
+
+| Characteristic | Value |
+|---|---|
+| VALUE ADDED TRAIT | SS |
+| RELATIVE MATURITY | 112 |
+| GDUS TO MID-POLLINATION | 1365 |
+| GDUS TO BLACK LAYER | 2800 |
+| PLANTING RATE | Med Low |
+| SILAGE PROVEN | No |
+| NEW PRODUCT | NO |
+| VARIETY | 01045328 |
+
+## Plant Description
+
+| Characteristic | Value |
+|---|---|
+| COB COLOR | Red |
+| KERNEL CAP COLOR | Yellow |
+| KERNEL ROW | 16 |
+
+## Growth
+
+| Characteristic | Value |
+|---|---|
+| EMERGENCE | 3 |
+| SEEDLING GROWTH | 3 |
+| ROOT STRENGTH | 3 |
+| STALK STRENGTH | 3 |
+| DROUGHT TOLERANCE | 3 |
+| GREENSNAP | 6 |
+| PLANT HEIGHT | Medium |
+| EAR PLACEMENT | Medium |
+
+## Harvest
+
+| Characteristic | Value |
+|---|---|
+| STAYGREEN | 3 |
+| HARVEST APPEARANCE | 3 |
+| DRYDOWN | 3 |
+| TEST WEIGHT | 2 |
+
+## Diseases
+
+| Characteristic | Value |
+|---|---|
+| NORTHERN CORN LEAF BLIGHT | 4 |
+| SOUTHERN CORN LEAF BLIGHT | 2 |
+| GRAY LEAF SPOT | 6 |
+| COMMON RUST | 2 |
+| SOUTHERN RUST | 5 |
+| EYE SPOT | 2 |
+| ANTHRACNOSE LEAF BLIGHT | 5 |
+| STEWART'S LEAF BLIGHT | 3 |
+| ANTHRACNOSE STALK ROT | 5 |
+| GOSS'S WILT | 6 |
+
+## Herbicide
+
+| Characteristic | Value |
+|---|---|
+| GROWTH REGULATORS SENSITIVITY | C |
+| SULFONYLUREAS SENSITIVITY | W |
+| ISOXAZOLES SENSITIVITY - PRE-EMERGENCE | A |
+
+## Silage Characteristics
+
+| Characteristic | Value |
+|---|---|
+| NDFD 24 HR | 3 |
+| NDFD 30 HR | 3 |
+| % OF STARCH | 3 |
+| IVSD7HR | 2 |
+| SILAGE YIELD | 3 |
+| MILK PER TON | 3 |
+| MILK PER ACRE | 3 |
+
+## Other
+
+| Characteristic | Value |
+|---|---|
+| CORN LETHAL NECROSIS | - |
+
+## Regional seed-guide listings
+
+- **Southeast (AL/FL/GA) 2026** — agronomist: Eddie Beasley
+- **Southeast (AL/FL/GA) 2026#2** — agronomist: Vint Hicks
+- **Southeast (AL/FL/GA) 2025#2** — agronomist: Vint Hicks
+- **Southeast (AL/FL/GA) 2025#2** — agronomist: Eddie Beasley