docs(decisions): D-223 #951 implementation notes + Gemma naming methodology

- Add docs/gemma-naming-methodology.md preserving the corridor-aware LLM
  place-naming approach (sector palettes, two-stage register selection +
  generation, few-shot prompting, KV-cache refresh, dedup, Earth-major
  blocklist, deterministic fallback) as institutional knowledge after the
  pipeline's retirement.
- Add an implementation-status note to D-223 recording what #951 did
  (generator + naming cluster retired, import_economics owns the atlas
  index, population deferred to #955, Sol exempt, dup bug fixed).
- CHANGELOG entries.

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

decisions/architecture.md

@@ -1430,6 +1430,7 @@ Technical foundation decisions that constrain implementation: engine, client-ser
 
 - **Rationale:** Authored positions created a hand/procedural split that (per D-207's own rationale) was impossible to query, diff, or validate. Reducing authored content to a name pool removes that split entirely while preserving the flavor that makes places feel hand-made — names follow culture and region, geometry follows terrain and economics. The templates were leftover scaffolding from before fully-generative placement; removing them simplifies the pipeline without losing any canonical place.
 - **Implementation:** tracked under Phase 4 (epic #750) — strip markers to names, remove template machinery + `reserved` pinning, update the atlas pipeline/schema, regen. Historical archives (sprints, workshops, audits, CHANGELOG, atlas proposals) are left untouched.
+- **Implementation status (#951, 2026-05-22): done.** All 2,398 `markers.json` reduced to a names-only pool (25,264 names; 349 city names across 271 bodies). The Python atlas **geometry generator** (`generate_atlas.py`) and the **LLM naming cluster** (`gemma_naming.py`, `naming_core.py`, `apply_name_fixes.py`, their tests/QA, the `fix_fewshot_bleed`/`prune_atlas_features` geometry tools, the redundant `import_city_names.py`, and the `run-atlas-naming.sh` runner) were retired — the procedural server cascade (Phase 4) supersedes them. The Gemma prompting methodology is preserved in [docs/gemma-naming-methodology.md](../docs/gemma-naming-methodology.md). Shared atlas-DB utilities moved to `tooling/planet-gen/atlas_common.py`; **`import_economics.py` is now the sole regen-db generator that owns the atlas index** — it loads the names pool into `atlas_city_names` and empties the 8 geometry tables (`atlas_cities/roads/railroads/pois/rivers/oceans/mountain_ranges/body_grids`), which the cascade fills. `population`/`kind`/`settlement_class` on `atlas_city_names` are **deferred to placement (#955)** — `attractor_matching` reads them at 0/default until then; that empty state is the gap the cascade closes. The `reserved=1` corp-HQ cross-reference stays (corp HQ names are real places). A latent duplicate-accumulation bug in name population (no clear + no unique constraint) was fixed with a deterministic rebuild. **Sol (system `GJ 0`) is permanently exempt from the normal generators:** it uses real Earth/Mars/Luna geography via the offline `sol_import.py` (left in place for future scripted integration), so its bodies keep geometry-bearing `markers.json` as preserved positional config and are skipped by the names-pool importer — Sol names will come from its own integration, not the cascade. `make regen-db` green.
 - **Raised by:** Jeroen, 2026-05-22 — resolving the open question on merging preconfigured content into the deterministic cascade.
 - **Cross-reference:** [D-207](#d-207-fully-generative-placement--markersjson-stripped-to-topographic-features) (superseded — names-only, no reserved pinning), [D-191](#d-191) §8 (markers format — names-only), [D-208](#d-208) (drainage → river courses), [D-211](#d-211) (settlement placement), [D-199](#d-199) (economic read set), [D-222](#d-222) (lore≠code names on generated geometry)
 - **Dissent:** None