feat: experiment results — HN spectral database + q-profile sweep

Adds measured results from two CPU runs:

1. HN spectral database (run 019f2c52):
   Hoffman bound on 6 graphs. Tight for regular (path, cycle, complete),
   gap=1 for unit-distance (Moser spindle, Golomb graph). Pattern
   suggests spectral detection loses exactly 1 color for unit-distance graphs.

2. q-profile sweep (run 019f2d9c):
   Sweeps q = L₁/L₀ over coprime fractions. REFUTES the prediction
   that q < 1 (poloidal-dominated) is Sidon-favorable: q > 1 has
   100% Sidon rate vs 40-60% for q < 1. The toroidal/poloidal analogy
   doesn't directly control Sidon-ness via the q-ratio direction.

   For non-Sidon label sets: 0% Sidon at ALL q values (q-profile
   cannot CREATE Sidon from non-Sidon, only PRESERVE it).

All scripts, formal modules, and docs already committed to main.
This commit adds the experiment artifact JSONs and EVALs.

.openresearch/artifacts/crt_qprofile_sweep_eval.md

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+# CRT q-Profile Safety Factor Sweep
+
+**Experiment:** crt_qprofile_sweep
+**Date:** 2026-07-04T14:52:24Z
+**SHA-256:** `9e3c89352141e4d707215ef7b01b0eb1c70193d854774f7e2f4eaecd24fddfb4`
+
+## Summary: Sidon Rate by q-Regime
+
+| Label set | Total | Sidon | Rate | q<1 total | q<1 Sidon | q<1 rate | q>1 total | q>1 Sidon | q>1 rate | Simple q Sidon | Non-simple Sidon | Best q |
+|-----------|-------|-------|------|-----------|-----------|----------|-----------|-----------|----------|----------------|------------------|-------|
+| sidon_pow2 | 25 | 22 | 88.0% | 5 | 2 | 40.0% | 20 | 20 | 100.0% | 22 | 0 | 5/7 |
+| sidon_singer5 | 25 | 23 | 92.0% | 5 | 3 | 60.0% | 20 | 20 | 100.0% | 23 | 0 | 3/7 |
+| nonsidon_seq5 | 25 | 0 | 0.0% | 5 | 0 | 0.0% | 20 | 0 | 0.0% | 0 | 0 | 2/7 |
+
+## Predictions Tested
+
+1. **q < 1 (poloidal-dominated) should have higher Sidon rate than q > 1**
+   - This is the toroidal/poloidal refinement prediction
+   - If confirmed: poloidal resolution matters for Sidon structure
+
+2. **Simple rational q should have LOWER Sidon rate than non-simple q**
+   - This is the R2 cross-pair coprimality prediction
+   - Simple rationals = resonant surfaces = Sidon collapse
+
+3. **Best q should be < 1 and not a simple rational**
+   - Optimal q-profile is poloidal-dominated and irrational

.openresearch/artifacts/hn_spectral_database.json

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+{
+  "experiment": "hn_spectral_database",
+  "timestamp": "2026-07-04T08:50:51Z",
+  "include_degrey": false,
+  "graphs": [
+    {
+      "description": "Moser spindle",
+      "n_vertices": 7,
+      "n_edges": 12,
+      "lambda_max": 3.645751311065,
+      "lambda_min": -2.0,
+      "hoffman_bound": 2.822875655532,
+      "chi_hoffman": 3,
+      "welch_wynn": null,
+      "chi_welch_wynn": null,
+      "best_spectral_lower_bound": 3,
+      "chi_known": 4,
+      "gap": "gap=1"
+    },
+    {
+      "description": "Golomb graph (8 vertices, 10 edges)",
+      "n_vertices": 8,
+      "n_edges": 10,
+      "lambda_max": 2.681330643605,
+      "lambda_min": -2.323404276086,
+      "hoffman_bound": 2.154052556071,
+      "chi_hoffman": 3,
+      "welch_wynn": null,
+      "chi_welch_wynn": null,
+      "best_spectral_lower_bound": 3,
+      "chi_known": 4,
+      "gap": "gap=1"
+    },
+    {
+      "description": "Empty graph (10v baseline)",
+      "n_vertices": 10,
+      "n_edges": 0,
+      "lambda_max": 0.0,
+      "lambda_min": 0.0,
+      "hoffman_bound": null,
+      "chi_hoffman": null,
+      "welch_wynn": null,
+      "chi_welch_wynn": null,
+      "best_spectral_lower_bound": null,
+      "chi_known": 1,
+      "gap": "?"
+    },
+    {
+      "description": "Path graph P10 (baseline)",
+      "n_vertices": 10,
+      "n_edges": 9,
+      "lambda_max": 1.918985947229,
+      "lambda_min": -1.918985947229,
+      "hoffman_bound": 2.0,
+      "chi_hoffman": 2,
+      "welch_wynn": null,
+      "chi_welch_wynn": null,
+      "best_spectral_lower_bound": 2,
+      "chi_known": 2,
+      "gap": "tight"
+    },
+    {
+      "description": "Cycle C5 (baseline)",
+      "n_vertices": 5,
+      "n_edges": 5,
+      "lambda_max": 2.0,
+      "lambda_min": -1.61803398875,
+      "hoffman_bound": 2.2360679775,
+      "chi_hoffman": 3,
+      "welch_wynn": null,
+      "chi_welch_wynn": null,
+      "best_spectral_lower_bound": 3,
+      "chi_known": 3,
+      "gap": "tight"
+    },
+    {
+      "description": "Complete K4 (baseline)",
+      "n_vertices": 4,
+      "n_edges": 6,
+      "lambda_max": 3.0,
+      "lambda_min": -1.0,
+      "hoffman_bound": 4.0,
+      "chi_hoffman": 4,
+      "welch_wynn": null,
+      "chi_welch_wynn": null,
+      "best_spectral_lower_bound": 4,
+      "chi_known": 4,
+      "gap": "tight"
+    }
+  ],
+  "sha256": "6af248bdf51d4a90b6e286e4decc33f60b153b4b162c677ecfbaf9f12b20641c"
+}

.openresearch/artifacts/hn_spectral_database_eval.md

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+# Hadwiger-Nelson Spectral Database
+
+**Date:** 2026-07-04T08:50:51Z
+**SHA-256:** `6af248bdf51d4a90b6e286e4decc33f60b153b4b162c677ecfbaf9f12b20641c`
+**Includes de Grey:** False
+
+## Spectral Bounds Comparison
+
+| Graph | n | e | λ_max | λ_min | Hoffman | χ_Hoff | Welch-Wynn | χ_WW | Known χ | Gap |
+|-------|---|---|-------|------|---------|--------|------------|------|---------|-----|
+| Moser spindle | 7 | 12 | 3.6458 | -2.0000 | 2.8229 | 3 | N/A | None | 4 | gap=1 |
+| Golomb graph (8 vertices, 10 edges) | 8 | 10 | 2.6813 | -2.3234 | 2.1541 | 3 | N/A | None | 4 | gap=1 |
+| Empty graph (10v baseline) | 10 | 0 | 0.0000 | 0.0000 | inf | None | N/A | None | 1 | ? |
+| Path graph P10 (baseline) | 10 | 9 | 1.9190 | -1.9190 | 2.0000 | 2 | N/A | None | 2 | tight |
+| Cycle C5 (baseline) | 5 | 5 | 2.0000 | -1.6180 | 2.2361 | 3 | N/A | None | 3 | tight |
+| Complete K4 (baseline) | 4 | 6 | 3.0000 | -1.0000 | 4.0000 | 4 | N/A | None | 4 | tight |
+
+## Key Findings
+
+1. **Hoffman bound** (χ ≥ 1 - λ_max/λ_min): classic spectral bound
+2. **Welch-Wynn bound** (χ ≥ n/(n - λ_max)): another spectral bound
+3. **Gap**: difference between best spectral bound and known chromatic number
+   - 'tight' = spectral bound matches known χ
+   - 'gap=N' = spectral bound is N below known χ
+
+The gap measures how much chromatic information is NOT captured
+by the spectrum. For the octagon principle, a tight spectral bound
+means the nonlinear property (colorability) IS detectable from
+the linear invariant (eigenvalue spectrum).