Retire SPECS.md

The spec served as the build plan; the built thing now documents
itself — man pages for the interface, the test suite for behavior,
ADRs in redoal for the design conversation. Removing it beats letting
it drift.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -55,7 +55,7 @@ jobs:
           cp dist/config.toml "$PKG/config.toml.example"
           scdoc < dist/varde.8.scd > "$PKG/man/varde.8"
           scdoc < dist/varde-ctl.1.scd > "$PKG/man/varde-ctl.1"
-          cp README.md SPECS.md LICENSE-MIT LICENSE-APACHE "$PKG/"
+          cp README.md LICENSE-MIT LICENSE-APACHE "$PKG/"
           tar czf "$PKG.tar.gz" "$PKG"
           sha256sum "$PKG.tar.gz" > "$PKG.tar.gz.sha256"