fix(telemetry): update collector config + tempo datasource + design doc for simplified attr names

- otel-collector-config.yaml: spanmetrics dimensions use new bare names.
- tempo.yaml: TraceQL filter tags use new bare names.
- 02-design-decisions.md: strip xrpl.txq.* prefix from planned attrs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

OpenTelemetryPlan/02-design-decisions.md

@@ -302,9 +302,9 @@ resource::SemanticConventions::SERVICE_INSTANCE_ID = <node_public_key_base58>
 #### TxQ Attributes
 
 ```cpp
-"xrpl.txq.queue_depth"      = int64    // Current queue depth
-"xrpl.txq.fee_level"        = int64    // Fee level of transaction
-"xrpl.txq.eviction_reason"  = string   // Why transaction was evicted
+"queue_depth"      = int64    // Current queue depth (planned, not yet implemented)
+"fee_level"        = int64    // Fee level of transaction (planned, not yet implemented)
+"eviction_reason"  = string   // Why transaction was evicted (planned, not yet implemented)
 ```
 
 #### Fee Attributes

docker/telemetry/grafana/provisioning/datasources/tempo.yaml

@@ -102,17 +102,17 @@ datasources:
             type: static
           # Phase 2: RPC tracing filters
           - id: rpc-command
-            tag: xrpl.rpc.command
+            tag: command
             operator: "="
             scope: span
             type: static
           - id: rpc-status
-            tag: xrpl.rpc.status
+            tag: rpc_status
             operator: "="
             scope: span
             type: dynamic
           - id: rpc-role
-            tag: xrpl.rpc.role
+            tag: rpc_role
             operator: "="
             scope: span
             type: dynamic
@@ -216,12 +216,12 @@ datasources:
             scope: span
             type: dynamic
           - id: txq-status
-            tag: xrpl.txq.status
+            tag: txq_status
             operator: "="
             scope: span
             type: dynamic
           - id: txq-ter-code
-            tag: xrpl.txq.ter_code
+            tag: ter_code
             operator: "="
             scope: span
             type: dynamic

docker/telemetry/otel-collector-config.yaml

@@ -64,11 +64,11 @@ connectors:
       explicit:
         buckets: [1ms, 5ms, 10ms, 25ms, 50ms, 100ms, 250ms, 500ms, 1s, 5s]
     dimensions:
-      - name: xrpl.rpc.command
-      - name: xrpl.rpc.status
+      - name: command
+      - name: rpc_status
       - name: xrpl.consensus.mode
-      - name: xrpl.consensus.close_time_correct
-      - name: xrpl.tx.local
+      - name: close_time_correct
+      - name: local
       - name: xrpl.tx.suppressed
       - name: xrpl.peer.proposal.trusted
       - name: xrpl.peer.validation.trusted