chore(packaging): initialise compass project tracking

Adds pm/compass.toml with five workstreams (theme, logo, quarto, helpers,
packaging), the journal and decision-record scaffold, and a composed
.roborev.toml carrying nine project-specific review rules derived from the
package's actual conventions.

Also adds AGENTS.md as the cross-tool conventions file, wires project memory
into .agent/memory/ so it travels between machines, and untracks
tests/testthat/Rplots.pdf, which churned on every test run.

.gitignore

@@ -1,4 +1,11 @@
-.Rproj.user
-.Rhistory
-.RData
-.Ruserdata
+.Rproj.user
+.Rhistory
+.RData
+.Ruserdata
+.compass-cache/
+# roborev snapshots
+/.roborev/
+
+# Test run debris
+tests/testthat/Rplots.pdf
+tests/testthat/_problems/