feat(session): show session start time + elapsed duration in list (#696)

[RyderFreeman4Logos]

Summary

• csa session list previously only exposed LAST ACCESSED. When monitoring concurrent sessions it was hard to tell when each one started or whether a slow session was stuck.
• Add STARTED and ELAPSED columns. STARTED comes from session metadata or falls back to the ULID-encoded creation timestamp. ELAPSED is compact (45s / 3m / 1h23m / 2d4h) and uses wall-clock-vs-now for active sessions, last-accessed-minus-created for terminal phases.

Closes #696.

Test plan

• cargo test -p cli-sub-agent session
• cargo test --workspace
• just pre-commit

🤖 Generated with Claude Code

[RyderFreeman4Logos]

Local pre-PR cumulative review (csa review --range main...HEAD, tier-4-critical, session 01KPNXX4BZM949GZB6SQQ5SM4R):

• reviewer 2 (codex): CLEAN. findings.toml: findings = []. severity_summary: {critical: 0, high: 0, medium: 0, low: 0, info: 0}. overall_risk: low. "No blocking correctness, contract, or security regressions were identified."

Merging. Narrow UX feature, additive columns, no behavior change elsewhere.

[gemini-code-assist]

Code Review

This pull request bumps the version to 0.1.449 and enhances the session listing functionality by adding 'STARTED' and 'ELAPSED' columns to the CLI output and JSON representation. It introduces helper functions for formatting durations and provides a fallback mechanism for legacy sessions missing the created_at field by decoding the timestamp from the session's ULID. Feedback was provided regarding the efficiency of the session list loop, specifically suggesting that the current time should be captured once before the loop rather than calling Utc::now() for every iteration.

[gemini-code-assist]

Calling chrono::Utc::now() inside the loop for every session is inefficient and can lead to inconsistent 'ELAPSED' times across the list if the list is long. It is better to capture the current time once before the loop starts.

Suggested change

	for session in sessions {
	// Truncate ULID to 11 chars for readability
	let short_id =
	&session.meta_session_id[..11.min(session.meta_session_id.len())];
	let status_str = resolve_session_status(&session);
	let started_str = format_started_at(session_created_at(&session));
	let elapsed_str = format_elapsed(&session, &status_str, chrono::Utc::now());
	let now = chrono::Utc::now();
	for session in sessions {
	// Truncate ULID to 11 chars for readability
	let short_id =
	&session.meta_session_id[..11.min(session.meta_session_id.len())];
	let status_str = resolve_session_status(&session);
	let started_str = format_started_at(session_created_at(&session));
	let elapsed_str = format_elapsed(&session, &status_str, now);