fix: keep internal section numbers out of runtime messages

Four messages that reach an operator or an API client cited sections
of a specification nobody outside the project can read:

- the unimplemented archive store error from config load
- the running-server cap refusal, from both the user wake and the
  internal wake
- the missing memory ceiling guard, in the API and in felis apply

The references are gone and the wording is otherwise unchanged. Each
message still says what went wrong and, where there is one, what to
do about it. The test for the archive store message checks for the
tarLocal remediation, which is still there.

cmd/felis/apply.go

@@ -220,7 +220,7 @@ func buildMinecraftServerFromApplyRequest(req applyRequest, namespace string) (*
 	}
 	memLim, ok := limits[corev1.ResourceMemory]
 	if !ok || memLim.IsZero() {
-		return nil, fmt.Errorf("internal error: refusing to create a server without a memory ceiling (§22)")
+		return nil, fmt.Errorf("internal error: refusing to create a server without a memory ceiling")
 	}
 
 	// ---- storage ----

internal/api/handlers_internal.go

@@ -149,7 +149,7 @@ func (a *API) handleInternalWake(w http.ResponseWriter, r *http.Request) {
 	}
 	if !ok {
 		writeError(w, r, newError(http.StatusServiceUnavailable, "at_capacity",
-			"the cluster is at its running-server cap (spec §9.1); retry once a server stops"))
+			"the cluster is at its running-server cap; retry once a server stops"))
 		return
 	}
 

internal/api/handlers_user.go

@@ -52,7 +52,7 @@ func (a *API) handleWake(w http.ResponseWriter, r *http.Request) {
 	}
 	if !ok {
 		writeError(w, r, newError(http.StatusServiceUnavailable, "at_capacity",
-			"the cluster is at its running-server cap (spec §9.1); retry once a server stops"))
+			"the cluster is at its running-server cap; retry once a server stops"))
 		return
 	}
 
@@ -526,7 +526,7 @@ func resolveResources(memory string, rr *resourceRequest) (string, corev1.Resour
 	memLim, ok := limits[corev1.ResourceMemory]
 	if !ok || memLim.IsZero() {
 		return "", corev1.ResourceRequirements{}, newError(http.StatusInternalServerError, "internal",
-			"refusing to create a server without a memory ceiling (§22)")
+			"refusing to create a server without a memory ceiling")
 	}
 
 	return deriveJavaHeap(memLim), corev1.ResourceRequirements{Limits: limits, Requests: requests}, nil

internal/config/config.go

@@ -300,7 +300,7 @@ func (c *Config) Validate() error {
 		return fmt.Errorf("config: [archive] store %q is not one of tarLocal|tarS3|volumeSnapshot|longhorn", c.Archive.Store)
 	}
 	if _, ok := implementedArchiveStores[c.Archive.Store]; !ok {
-		return fmt.Errorf("config: [archive] store %q is recognized by §19 but not implemented in this build — only tarLocal is supported; set store = \"tarLocal\"", c.Archive.Store)
+		return fmt.Errorf("config: [archive] store %q is not implemented in this build — only tarLocal is supported; set store = \"tarLocal\"", c.Archive.Store)
 	}
 	switch c.K8s.EgressMode {
 	case "loadbalancer", "nodeport":