Standardize timestamps to ISO 8601 UTC across all logs and decisions #84

Problem

User feedback: "please make sure we're stamping decisions and things logged to disk with date-time stamps not just the date. and they should prolly be utc dates. something that works everywhere as much as possible."

Current state is inconsistent:

• Orchestration logs: Use ISO 8601 datetime format 2026-02-08T0412 (UTC, filenames)
• Session logs: Use date-only format 2026-02-08-{topic}.md (filenames)
• Decisions.md headers: Use date-only format ### 2026-02-07: Team formation
• Index.js timestamps: Mix of formats:
  • new Date().toISOString() for casting registry (full ISO 8601 with timezone)
  • .toISOString().split('T')[0] for import date (date-only)
  • .toISOString().replace(/[:.]/g, '-').replace('T', '-').slice(0, 19) for archive folders

Proposal

Standardize on ISO 8601 UTC timestamps everywhere:

• Format: YYYY-MM-DDTHH:MM:SSZ (e.g., 2026-02-16T18:45:23Z)
• Use new Date().toISOString() consistently across all Squad code
• Human-readable, sorts correctly, unambiguous timezone (always UTC)
• Works everywhere (cross-platform, cross-locale)

Changes Needed

1. Decision headers:

   • Change from: ### 2026-02-07: Team formation
   • Change to: ### 2026-02-07T19:32:15Z: Team formation
   • Or create a new section: **Date:** 2026-02-07T19:32:15Z below header

2. Session log filenames:

   • Change from: .ai-team/log/2026-02-08-{topic}.md
   • Change to: .ai-team/log/2026-02-08T0512-{topic}.md (matches orchestration log pattern)
   • This makes chronological order unambiguous when multiple sessions happen same day

3. Scribe spawn template:

   • Update template at line 785: 1. Log this session to .ai-team/log/{timestamp}-{topic}.md:
   • Change {YYYY-MM-DD} placeholders to {timestamp} (ISO 8601)
   • Update ceremony log pattern at line 963 similarly

4. Decision inbox filenames:

   • Change from: .ai-team/decisions/inbox/copilot-directive-{timestamp}.md
   • Verify {timestamp} expands to full ISO 8601 (not date-only)

5. Templates:

   • templates/history.md line 6: - **Created:** {date} → use full timestamp
   • templates/roster.md line 60: - **Created:** {date} → use full timestamp
   • templates/scribe-charter.md references to {date} → use {timestamp}

Why This Matters

• Debugging: Full timestamps let us reconstruct exact session sequences when troubleshooting
• Distributed teams: UTC removes timezone ambiguity (no "was that 3pm EST or PST?")
• Automation: ISO 8601 is the universal standard for logs, APIs, and tooling
• Sorting: Lexicographic filename sort = chronological order
• Audit trail: Important for compliance, security reviews, and incident response

Acceptance Criteria

• All decision headers include full UTC timestamp
• All log filenames use ISO 8601 datetime format
• squad.agent.md spawn templates use {timestamp} placeholder (ISO 8601)
• Templates updated to use full timestamp instead of date-only
• Test coverage for timestamp format consistency
• Migration plan for existing repos with date-only logs (or accept both)

Non-Goals (Keep Date-Only)

• Git commit messages can stay date-only (e.g., feat(docs): ...) — that's a Git convention
• Release tags can stay semantic version + date (e.g., v0.4.1-2026-02-16)