Topdata Migration (#2)

Native topdata migration summary

- Replaced the legacy 2dabuilder runtime path with the native topdata builder.
- Native build, validate, compare, and convert flows now cover the canonical topdata pipeline.
- compare-topdata is now a native self-check; legacy reference-builder runtime usage was removed.
- Parts generation follows the native asset-scan contract and uses sow-assets via project asset resolution.
- Generated feat families, class-feat injects, masterfeat/successor expansion, and dataset-derived feat generation were brought to parity and regression-covered.
- Remaining mirrored datasets were migrated into native-owned canonical data while preserving lock IDs.
- normalize-topdata bridge behavior and migration-era ownership markers were removed.
- Documentation was rewritten around the native workflow and active contracts were cleaned up.
- Final hardening pass removed stale validator assumptions and cleaned ignored/generated artifacts for PR readiness.

Reviewed-on: https://gitea.westgate.pw/ShadowsOverWestgate/sow-tools/pulls/2
Co-authored-by: vickydotbat <vickydotbat@tutamail.com>
Co-committed-by: vickydotbat <vickydotbat@tutamail.com>

README.md

@@ -37,10 +37,11 @@ tools/             built development binary output
 - `sow-assets` uses `sow-toolkit` for `build-haks` and validation
   - validation now fails early if duplicate asset resources would collide inside the same generated HAK
   - duplicate resources split across different HAK groups remain warnings because later HAK order can still override earlier content at runtime
-- `sow-module` now also uses `sow-toolkit` for the early topdata bridge:
+- `sow-module` now also uses `sow-toolkit` for topdata:
   - `validate-topdata`
   - `build-topdata`
   - `compare-topdata`
+  - `convert-topdata`
 
 During development, sibling repositories can point at `../sow-tools/tools/sow-toolkit`. For pinned releases, each consumer repo can instead carry its own copy at `tools/sow-toolkit`.
 
@@ -57,15 +58,23 @@ Consumer repos can fetch those binaries into their local `tools/` directory with
 - `install-tool.sh` on Linux/macOS
 - `install-tool.ps1` on Windows
 
-## TopData Migration
+## TopData
 
-The topdata rebuild is now staged in this repo.
+The native topdata system is implemented in this repo and authored in `sow-module`.
 
-Current state:
+High-level ownership split:
 
-- the new command surface exists in `sow-toolkit`
-- `sow-module/topdata/` is the new long-term source home
-- `build-topdata` currently bridges through the Python builder in `sow-dev` for authoritative output generation
-- native Go merge/build parity is still a follow-up milestone
+- `sow-tools`
+  - owns the `sow-toolkit` implementation
+  - owns topdata validation, build, compare, conversion, and dataset-resolution logic
+- `sow-module`
+  - owns canonical topdata authored data under `topdata/data/`
+  - owns the user-facing topdata workflow scripts
 
-See [TOPDATA_HANDOFF_2026-04-02.md](./TOPDATA_HANDOFF_2026-04-02.md) for the current handoff and migration notes.
+For a human-readable front-to-back explanation of how the native topdata builder works
+and how to use it, see:
+
+- [sow-module/topdata/README.md](../sow-module/topdata/README.md)
+
+Important topdata contracts still live here under `internal/topdata/` because they are
+code-adjacent implementation contracts, not user workflow docs.