Mark Seriatim source installation complete

docs/roadmap/features/0001-seriatim-source-installation.md

@@ -1,6 +1,6 @@
 # Feature 0001: Seriatim Source Installation
 
-Status: proposed
+Status: done
 
 ## Summary
 
@@ -155,3 +155,17 @@ After review, the source-build conventions may be adopted by the Audita,
 Scriptorium, Notarius, and Narratio roles. Generalization into shared tooling,
 prebuilt-binary installation, removal behavior, and dedicated multi-platform
 test infrastructure remain deferred until concrete experience justifies them.
+
+## Completion Evidence
+
+- `ansible-role-seriatim` commits `ac35c1f` through `efd4734` implement the
+  staged role contract, source installation, reproducible build, and integration
+  coverage.
+- Remediation commits `c6c1907` through `6fb1aa2` close all findings recorded in
+  `docs/roadmap/remediation.md`, including malformed state and metadata drift.
+- The complete integration suite passes on the local Ubuntu 26.04 development
+  host, restores the default installation, and finishes with a clean idempotent
+  convergence.
+- The verified installation reports `seriatim version v1.5.0`, uses upstream
+  commit `0fc92f364316c874d366b00cdc884a33e1900b25`, and has consistent source,
+  binary, ownership, and build-state metadata.