CI: remove k8s stages, fix the Docker-level pipeline green

Survey + fixes so the pipeline passes at the Docker level (no k8s).

- Remove k8s: drop the `sandbox-k8s` job (kind/Calico/--features k8s-tests) and the
  "Helm chart lints" gate step. release.yml was already k8s-clean.
- Rust job:
  - `cargo fmt --all` — fix pre-existing formatting drift (fmt --check was failing).
  - clippy -D warnings: fix 3 lib warnings (cm-brain sort_by_key→Reverse, cm-api
    fleet.rs doc list indentation, node_rules map_or→is_none_or).
  - Regenerate the .sqlx offline cache (was missing the cm-runtime run_loop test
    query → offline compile failed). DB-backed tests use testcontainers at runtime.
  - Set SQLX_OFFLINE=true on the rust + e2e jobs so query! macros compile against
    the committed cache deterministically (no DB needed at compile time).
- Frontend job:
  - Fix the 1 ESLint error (useAgentTelemetry: no setState-synchronously-in-effect;
    tag the slice with agentId + derive null on mismatch).
  - Fix 2 stale panel-params tests (`terminal` is a valid app id now; assert the
    current APP_IDS + use a genuinely-unknown id for the reject case).

Verified locally: fmt clean, clippy --all-targets -D warnings clean (offline),
frontend lint 0 errors, tsc clean, 86/86 frontend tests pass, build OK.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

.sqlx/query-47c1cee8591250819d22e87058c6011bebb77eaf93c1cfa2535db42221d8ecf3.json

@@ -0,0 +1,34 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT tokens_in, tokens_out, credits FROM usage_events\n               WHERE workspace_id = $1",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "tokens_in",
+        "type_info": "Int8"
+      },
+      {
+        "ordinal": 1,
+        "name": "tokens_out",
+        "type_info": "Int8"
+      },
+      {
+        "ordinal": 2,
+        "name": "credits",
+        "type_info": "Numeric"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      false,
+      false,
+      false
+    ]
+  },
+  "hash": "47c1cee8591250819d22e87058c6011bebb77eaf93c1cfa2535db42221d8ecf3"
+}