Rename neural experiments to descriptive paths (drop N* codes)

configs/neural/{N0,N1,N2,N5}.yaml -> {bridge,collapse,grounding,architectures}.yaml,
results dirs likewise. Updated experiment/output.dir fields, comments/docstrings, and
docs; regenerated the four result manifests (now carrying the real git commit). No
functional path resolution referenced the codes (the Makefile globs configs/neural/*.yaml
and tests use inline configs), so nothing breaks. 92 tests green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

configs/neural/bridge.yaml

@@ -0,0 +1,42 @@
+experiment: bridge_histogram
+kind: gen_lineage
+seed: 20260704
+n_replicates: 60
+generations: 200
+
+# Bridge / harness-faithfulness check (Layer 1.5 build-order Stage B): run the E2 grounding
+# phase-boundary sweep through the NEURAL runner with the histogram model, which is exactly
+# neutral Wright-Fisher drift with immigration. Stationary H must track the closed form
+# H_eq = H* * m(2n+m-1)/(n+2nm+m^2) and reproduce a critical g* << 1 — i.e. the neural
+# plumbing reproduces the analytic core before any real network is trained. R=1 so every
+# grounding policy reduces to the proportional immigration model H_eq is derived for.
+synthetic:
+  K: 200
+  R: 1
+  tail: zipf
+  zipf_s: 1.1
+  tail_frac: 0.5
+  tail_threshold: 1.0e-3
+  init: truth
+  style_len: 2
+  style_vocab: 4
+  id_base: 2
+
+model:
+  kind: histogram
+
+dynamics:
+  n: 200
+  grounding: {m: 0, policy: proportional}   # m is overwritten per g by the sweep
+  remint: {enabled: false, period: null, H_gate: null}
+
+metrics:
+  kl_floor: 1.0e-9
+  support_eps: 1.0e-9
+
+sweep:
+  - param: g
+    values: [0.0, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, 0.4]
+
+output:
+  dir: results/bridge