RTECO-1017 - Detect agent + CI invocation context, enrich metrics wit…

[fluxxBot]

…h agent/is_agent/is_interactive

• All tests passed. If this feature is not already covered by the tests, I added new tests.
• All static analysis checks passed.
• This pull request is on the master branch.
• I used gofmt for formatting the code before submitting the pull request.

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Summary

Adds detection of CLI invocation context — agent (Claude, Cursor, Gemini, Goose, Copilot, Windsurf, etc.), CI provider, and stdin TTY — and enriches the existing
jfcli_commands_count metric with the new dimensions.

Motivation

differentiate human / CI / agent invocations of jf. Backend currently can't tell whether a command came from a developer's desktop, a CI runner, or an AI agent. Without this, we can't measure agent-driven usage or separate human vs automated traffic.

Changes

• New common/commands/execution_context.go — single source of truth for invocation context. DetectExecutionContext() returns agent name, CI system, TTY presence, and
  propagated trace ID.
• New common/commands/execution_context_test.go — unit tests covering each agent env var, CI providers, trace ID gating, and no-env fallback.
• Extended utils/metrics/metrics.go — MetricsData gains IsAgent, Agent, IsInteractive fields (additive, omitempty).
• Updated common/commands/metrics_collector.go — CollectMetrics populates the new fields via DetectExecutionContext.

Detection

Agent identity is matched against an env-var table (first match wins, then generic AGENT fallback):

Agent	Env vars
claude	CLAUDECODE, CLAUDE_CODE_ENTRYPOINT
gemini	GEMINI_CLI
goose	GOOSE_TERMINAL
cursor	CURSOR_AGENT, CURSOR_TRACEID
copilot	COPILOT_CLI
kilocode	KILO_IPC_SOCKET_PATH, KILO_SERVER_PASSWORD
roo_code	ROO_CODE_IPC_SOCKET_PATH
replit	REPLIT_AGENT
windsurf	WINDSURF_SESSION_ID
aider	AIDER_MODEL
codex	CODEX_HOME

CI detection reuses the existing detectCISystem() provider list (Jenkins, Travis, CircleCI, GitHub Actions, GitLab, Buildkite, Bamboo, Azure DevOps, TeamCity, Drone, Bitbucket,
AWS CodeBuild, plus generic fallbacks).

TraceID is gated on agent identity — only Cursor's CURSOR_TRACEID is honored, and only when the detected agent is cursor. Prevents stale leakage from outer shells.