Retire legacy reference data and the external command catalog (#302)

- Remove xtask/data/fusion-catalog.tsv and xtask/data/fusion-ids.tsv.
- Remove the legacy command-id table (crates/engine/src/legacy_ids.rs) and its use in
  find_command and in the shortcut, recents and pinned-command loaders. Only SolidCraft's
  dotted ids name commands; any other id is an unknown command.
- Boundary Fill's id becomes solid.boundary_fill.
- Replace the parity report with SolidCraft's own feature checklist: `cargo xtask features`
  writes docs/features.md from the command registry.
- docs/oracle.md, docs/step-import.md (corpus section) and docs/iges-import.md: reference
  results are being rebuilt on analytic and open-source (FreeCAD) values; see #292.
  `cargo xtask oracle` and `cargo xtask step-corpus [--iges]` write these placeholders.
- AGENTS.md, CLAUDE.md, CONTRIBUTING.md, README.md, ROADMAP.md and the book describe
  SolidCraft as independent, with reference tests on analytic values and open-source tools,
  and agents do not drive or extract data from commercial CAD products.


Claude-Session: https://claude.ai/code/session_01RjGw4gA5ZvKrU8MQP6sBgT

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

docs/book/src/dev/architecture.md

@@ -7,7 +7,7 @@ SolidCraft is a Cargo workspace in layers. A crate only depends on crates in low
 
 The web app, `apps/solvecraft-web`, is the desktop front end compiled to wasm with
 [trunk](https://trunkrs.dev). `xtask` holds the repository's own tooling: `cargo xtask ci`,
-`layers`, `assets`, `oracle`, `parity` and `book`.
+`layers`, `assets`, `features`, `oracle` and `book`.
 
 A few rules follow from the layering:
 

docs/book/src/dev/commands.md

@@ -24,8 +24,8 @@ before it runs, and a failing command leaves the document unchanged. Feature com
 feature to the timeline and let the document evaluate it; they validate their inputs first
 (units, ranges, references) and return `BadParams` instead of building a broken feature.
 
-Ids used before the 2026-10 rename still resolve through `crates/engine/src/legacy_ids.rs`, so
-old scripts, recipes, saved shortcuts and toolbar layouts keep working.
+Only the registry's own dotted ids name commands (matched ignoring case); any other id fails
+with `unknown command`.
 
 ## Adding a command
 

docs/book/src/dev/features.md

@@ -0,0 +1 @@
+{{#include ../../../features.md}}

docs/book/src/dev/parity.md

@@ -1 +0,0 @@
-{{#include ../../../parity.md}}