[ChrisJBurns]

Summary

• Adds the mcp.server.operation.duration histogram metric as defined by the OTEL MCP semantic conventions
• Records operation latency with spec-defined attributes: mcp.method.name, gen_ai.tool.name, gen_ai.operation.name, gen_ai.prompt.name, jsonrpc.protocol.version, network.transport, network.protocol.name, network.protocol.version, error.type
• Exports MCPHistogramBuckets for reuse by future metrics (e.g. mcp.server.session.duration)
• Adds warning log when MCP method cannot be determined (indicates middleware misconfiguration)
• Existing custom toolhive_mcp_* metrics are preserved for backward compatibility

Note: mcp.server.session.duration is intentionally deferred — it will be trivial to add after the session management architecture refactor (#38).

Test plan

• TestHTTPMiddleware_OperationDuration/tools/call — verifies metric recorded with tool attributes
• TestHTTPMiddleware_OperationDuration/prompts/get — verifies metric recorded with prompt attributes
• TestHTTPMiddleware_OperationDuration/non-MCP — verifies metric is NOT recorded for non-MCP requests
• task lint-fix passes with 0 issues
• task test passes

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 93.75000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 66.39%. Comparing base (9405bac) to head (42eafe8).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/telemetry/middleware.go	93.75%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3752      +/-   ##
==========================================
+ Coverage   66.36%   66.39%   +0.02%     
==========================================
  Files         427      427              
  Lines       41894    41926      +32     
==========================================
+ Hits        27803    27835      +32     
+ Misses      11976    11974       -2     
- Partials     2115     2117       +2     

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