Validate sourced physical material property cards and elastic stability (#934)

Adds the read-only material.properties.validate command: schema_version 1 engineering material cards in SI units are checked for numerical consistency and elastic stability, with derived isotropic moduli, missing conditions and sources needing review. Nothing is assigned or saved.

Thanks @0xlillith.

docs/features.md

@@ -1,6 +1,6 @@
 # Features
 
-SolidCraft's commands by area, generated by `cargo xtask features` from the command registry (`solidcraft-cli commands`). **343 commands.** Planned (registered, not built yet): 6. Every command runs the same way from the toolbar, a script, `solidcraft-cli exec <id> '<json>'`, the control channel and MCP; parameters are in the [command reference](book/src/reference/commands.md) (`cargo xtask book`). Status and plans: [ROADMAP](../ROADMAP.md).
+SolidCraft's commands by area, generated by `cargo xtask features` from the command registry (`solidcraft-cli commands`). **344 commands.** Planned (registered, not built yet): 6. Every command runs the same way from the toolbar, a script, `solidcraft-cli exec <id> '<json>'`, the control channel and MCP; parameters are in the [command reference](book/src/reference/commands.md) (`cargo xtask book`). Status and plans: [ROADMAP](../ROADMAP.md).
 
 ## Sketch (99)
 
@@ -432,7 +432,7 @@ SolidCraft's commands by area, generated by `cargo xtask features` from the comm
 |---|---|---|
 | Delete Face | `face.delete` | SOLID › MODIFY |
 
-## `material.*` (5)
+## `material.*` (6)
 
 | Command | Id | Toolbar |
 |---|---|---|
@@ -441,6 +441,7 @@ SolidCraft's commands by area, generated by `cargo xtask features` from the comm
 | New Physical Material | `material.create` | – |
 | Edit Physical Material | `material.edit` | – |
 | Delete Physical Material | `material.delete` | – |
+| Validate Physical Material Data | `material.properties.validate` | – |
 
 ## `mesh.*` (1)