feat(progression): json stores on a real filesystem (slice 8)

new progression.adapters project, no engine reference. Stores take a
directory path; Godot resolves user:// with GlobalizePath and passes it
in, which is what makes them testable at all - originally I'd written
this slice off as untestable.

version lives in a file envelope, not the snapshot, so the domain only
knows the current shape. A newer-build save reports Corrupt with a
reason instead of masquerading as "no save" and getting overwritten.

atomic write via temp + rename. One file per aggregate: saving a run
leaves the profile file byte-identical, asserted.

guard rail fixed - it was matching prose in doc comments, now anchored
to using-directives plus a project.assets.json check. 63 tests.

docs/plans/phase-a-progression-domain.md

@@ -40,11 +40,15 @@ No tests. Pure setup.
 **Guard rail for the whole phase:**
 
 ```sh
-grep -rn "using Godot" progression progression.tests --include=*.cs   # must print nothing
+# must print nothing — anchored to real using-directives
+grep -rnE "^\s*(global\s+)?using\s+Godot" progression progression.adapters progression.tests --include=*.cs
+# stronger, and cannot be fooled by wording: no project may resolve the engine assembly at all
+grep -c GodotSharp progression/obj/project.assets.json progression.adapters/obj/project.assets.json
 ```
 
-That single check is what ADR-0004 buys you. Scope it to `--include=*.cs` — an unscoped `grep -r` also matches
-prose in the `.csproj` comments and reports a false violation.
+That check is what ADR-0004 buys you. Match using-directives **anchored to the start of a line**: a bare
+`grep -r "using Godot"` also hits `.csproj` comments and doc comments that legitimately mention the engine in prose,
+and reports a false violation. The `project.assets.json` check is the one that cannot be fooled by wording.
 
 ---