docs: replace hardcoded namespace with <your-namespace> placeholder

* docs: update Headlamp install namespace references from kube-system to headlamp

Updates all documentation references to the Headlamp install namespace
from kube-system to headlamp as part of PRI-433.

In-scope files updated:
- README.md, SECURITY.md
- docs/getting-started/installation.md, quick-start.md, prerequisites.md
- docs/deployment/helm.md, kubernetes.md, production.md
- docs/troubleshooting/README.md, common-issues.md, rbac-issues.md
- docs/user-guide/configuration.md, rbac-permissions.md
- docs/TESTING.md, TROUBLESHOOTING.md, DEPLOYMENT.md

Out-of-scope (unchanged):
- Source files referencing upstream workload namespace
- RBAC manifests describing Polaris namespace (polaris ns is unchanged)
- NetworkPolicy namespaceSelector (API server runs in kube-system)
- design-decisions.md and ARCHITECTURE.md (URL hashes refer to cluster namespaces, not Headlamp install ns)

Co-Authored-By: Paperclip <noreply@paperclip.ing>

* fix: correct RBAC manifest per QA review (PRI-555)

- Remove rbac.authorization.k8s.io privilege escalation block
- Fix orphaned comment from round 1
- Add EOF newline
- Keep serviceaccounts/token for E2E auth (confirmed needed)
- Namespace already correct (privilegedescalation-dev)

Co-Authored-By: Paperclip <noreply@paperclip.ing>

* docs: replace hardcoded namespace with <your-namespace> placeholder

Users choose their own namespace for Headlamp. Replace all hardcoded
namespace references (headlamp, kube-system) in user-facing docs with
<your-namespace> so users substitute their own value.

Conventions:
- Helm install: --namespace <your-namespace> --create-namespace
- kubectl commands: -n <your-namespace>
- YAML metadata: namespace: <your-namespace>
- Prose: "the namespace where Headlamp is installed"

Out-of-scope references left untouched:
- kube-system in NetworkPolicy selectors (API server namespace)
- polaris namespace references (upstream workload namespace)
- Source code and test files

Refs: PRI-433

Co-Authored-By: Paperclip <noreply@paperclip.ing>

* docs: fix remaining hardcoded headlamp namespace to <your-namespace> placeholder

Prior commit was inconsistent — some files used <your-namespace> while
DEPLOYMENT.md, TROUBLESHOOTING.md and several troubleshooting/user-guide
docs still hardcoded headlamp as the namespace.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

---------

Co-authored-by: Chris Farhood <chris@farhood.org>
Co-authored-by: Paperclip <noreply@paperclip.ing>

docs/user-guide/configuration.md

@@ -317,7 +317,7 @@ kubectl -n polaris get rolebinding headlamp-polaris-proxy
 
 # Test permission
 kubectl auth can-i get services/proxy \
-  --as=system:serviceaccount:kube-system:headlamp \
+  --as=system:serviceaccount:<your-namespace>:headlamp \
   -n polaris \
   --resource-name=polaris-dashboard
 ```

docs/user-guide/rbac-permissions.md

@@ -65,7 +65,7 @@ metadata:
 subjects:
   - kind: ServiceAccount
     name: headlamp # Adjust to your Headlamp SA name
-    namespace: kube-system # Adjust to Headlamp's namespace
+    namespace: <your-namespace>
 roleRef:
   kind: Role
   name: polaris-proxy-reader
@@ -75,7 +75,7 @@ roleRef:
 **Adjust for your environment:**
 
 - `subjects[0].name` - Your Headlamp service account name (often `headlamp`)
-- `subjects[0].namespace` - Namespace where Headlamp runs (often `kube-system`)
+- `subjects[0].namespace` - Namespace where Headlamp is installed
 
 ### Step 3: Apply and Verify
 
@@ -91,7 +91,7 @@ kubectl -n polaris get rolebinding headlamp-polaris-proxy
 
 # Test permission
 kubectl auth can-i get services/proxy \
-  --as=system:serviceaccount:kube-system:headlamp \
+  --as=system:serviceaccount:<your-namespace>:headlamp \
   -n polaris \
   --resource-name=polaris-dashboard
 
@@ -109,7 +109,7 @@ In token-auth mode, **each user's own identity** is used for Kubernetes API requ
 With service account mode:
 
 - Single RoleBinding grants access to all Headlamp users
-- Kubernetes sees all requests as `system:serviceaccount:kube-system:headlamp`
+- Kubernetes sees all requests as `system:serviceaccount:<your-namespace>:headlamp`
 
 With token-auth mode:
 
@@ -267,7 +267,7 @@ metadata:
 subjects:
   - kind: ServiceAccount
     name: headlamp
-    namespace: kube-system
+    namespace: <your-namespace>
 roleRef:
   kind: Role
   name: polaris-proxy-reader
@@ -281,7 +281,7 @@ metadata:
 subjects:
   - kind: ServiceAccount
     name: headlamp
-    namespace: kube-system
+    namespace: <your-namespace>
 roleRef:
   kind: Role
   name: polaris-proxy-reader
@@ -411,7 +411,7 @@ Every plugin data fetch creates a Kubernetes API audit log entry.
   "level": "Metadata",
   "verb": "get",
   "user": {
-    "username": "system:serviceaccount:kube-system:headlamp"
+    "username": "system:serviceaccount:<your-namespace>:headlamp"
   },
   "sourceIPs": ["10.96.0.1"],
   "objectRef": {
@@ -494,7 +494,7 @@ If using a log aggregator (e.g., Elasticsearch), create filters to exclude or do
    ```bash
    # Service account mode
    kubectl auth can-i get services/proxy \
-     --as=system:serviceaccount:kube-system:headlamp \
+     --as=system:serviceaccount:<your-namespace>:headlamp \
      -n polaris \
      --resource-name=polaris-dashboard