fix: accept zero retention limits, retire Store() for typed accessors

Phase 8 (PROJECT_REVIEW_PLAN.md 8.1): 0 in MaxLogFiles/MaxLogAgeDays now
means "keep everything" end to end. runner.CleanupLogs already treated
<= 0 as disabled; validateConfig, the Settings form, and
loadOrCreateConfig's backfill were the only things making that state
unreachable.

Phase 9 (1.1, rolling up 1.2, 1.3, 7.3): added Service.Config() and
Service.Paths(), copying under mu, and converted every UI site that read
Service state through the raw *storage.Store returned by Store() (now
removed). jobs_view's pause control is now driven by refreshView reading
svc.Config().Paused on every event instead of only mirroring its own tap
handler, which makes it an actual consumer of SchedulerStateChanged.
mainwindow's event listener is a real type switch, and events.go's doc
comment no longer claims a compiler exhaustiveness check Go doesn't have.
Unexported the redundant SetAutostart/AutostartStatus package functions
in platform/autostart now that only the Manager methods are used outside
the package.

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

src/storage/store_test.go

@@ -183,6 +183,35 @@ func TestLoadOrCreateConfigCreatesDefaultsOnFirstRun(t *testing.T) {
 	}
 }
 
+// TestLoadOrCreateConfigPreservesZeroRetentionLimits verifies that 0 in
+// max_log_files / max_log_age_days is read back as 0 ("keep everything"), not
+// backfilled to the 100 / 30 defaults, since a config that already has the
+// field set is not the "field is missing" case loadOrCreateConfig backfills.
+func TestLoadOrCreateConfigPreservesZeroRetentionLimits(t *testing.T) {
+	dir := t.TempDir()
+	paths := Paths{
+		AppDir:     dir,
+		ConfigPath: filepath.Join(dir, ConfigFileName),
+	}
+	want := domain.DefaultConfig()
+	want.MaxLogFiles = 0
+	want.MaxLogAgeDays = 0
+	if err := writeJSON(paths.ConfigPath, want); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := loadOrCreateConfig(paths)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got.MaxLogFiles != 0 {
+		t.Errorf("MaxLogFiles: got %d, want 0 (unlimited)", got.MaxLogFiles)
+	}
+	if got.MaxLogAgeDays != 0 {
+		t.Errorf("MaxLogAgeDays: got %d, want 0 (unlimited)", got.MaxLogAgeDays)
+	}
+}
+
 // TestLoadOrCreateJobsSeedsSampleJobsOnFirstRun verifies that a missing
 // jobs.json is created with the sample jobs from defaultJobs, so a new user
 // sees scheduled and manual execution without inventing a command.