fix(agents): classify timeout-triggered claude aborts as agent_timeout

[niranjan94]

Problem

When a stage exceeds its timeoutMs, the timeout timer in ClaudeAgentAdapter calls controller.abort(). The Claude Agent SDK responds by throwing a generic Error("Claude Code process aborted by user") with no way to distinguish a wall-clock timeout from a deliberate caller-initiated abort.

That raw error escaped the agent event loop unwrapped, so reportFailure (src/orchestrator.ts) fell through to the catch-all internal kind. Failures surfaced to users as:

**Kind:** `internal`
Claude Code process aborted by user

which is misleading — nothing was aborted by a user, the stage simply ran past its timeout. Observed on a real triage run that was actively mid-investigation when the 5-minute timeout fired.

Fix

• Track whether our timeout timer fired the abort via a timedOut flag.
• In the event-loop catch, reclassify a timed-out raw error as AgentError("agent_timeout", ...).
• External aborts (caller-supplied AbortController) and intentional AgentErrors pass through unchanged.

This mirrors the pattern already present in src/agents/codex.ts, which classified timeouts correctly; only the Claude path was missing it.

Tests

Two new cases in test/agents/claude.test.ts:

• timeout-triggered abort → AgentError(agent_timeout)
• externally-triggered abort → not reclassified (passes through as a raw error)

Full suite: 288 passing. typecheck clean, lint exit 0, dist/index.cjs rebuilt.

[github-actions]

Shopfloor agent review: clean across 4/4 reviewers.

• No compliance violations: the dist bundle was rebuilt per the committed-bundle rule, file placement matches existing structure, and the change follows the documented AgentError timeout pattern.
• The timeout-reclassification logic is correctly implemented and matches the AgentError constructor and codex pattern; both new tests genuinely exercise the timeout and external-abort paths.
• Reviewed the timeout-reclassification diff in src/agents/claude.ts and its tests; the change only adjusts error handling and introduces no exploitable security issues.
• Inspected the diff for src/agents/claude.ts and test/agents/claude.test.ts (excluding the generated dist bundle); the timeout-reclassification change is minimal, well-named, and free of duplication or dead code.