tech-debt: normalize inline datetime.now(utc).isoformat() onto utc_timestamp() (#12726)

[mrveiss]

Thinking Path

Picked as an unblocked, purely mechanical issue. utc_timestamp() (autobot_shared/time_utils.py:49) is literally datetime.now(timezone.utc).isoformat(), so this is a consistency change with no behaviour delta — confirmed by comparing output formats including the +00:00 suffix.

The canonical definition itself is deliberately untouched: rewriting time_utils.utc_timestamp() to call itself would be infinite recursion.

What Changed

100 inline call sites across 44 files replaced with the canonical helper, imports added where missing.

Three things a blind find/replace would have shipped

Worth listing, because each was caught by verification rather than by the edit step:

1. A SyntaxError. My import-insertion regex matched the opening line of a multi-line from autobot_shared.tracing import ( block and inserted inside the parentheses, breaking initialization/lifespan.py (E999). flake8 caught it; the replace step had no idea. Every changed file is now AST-parsed.

2. Newly-unused imports. Removing the last inline use orphaned from datetime import datetime, timezone in 24 files — including two function-local (indented) imports that a top-level-only regex missed. Cleaned iteratively, driven by flake8 F401 output rather than guesswork, and only where genuinely unused: files still using datetime elsewhere keep it.

3. A comment-only rewrite. In drift_checker_test.py the sole occurrence was inside a comment, so the sweep edited prose and added an import nothing used. That file is reverted — a sweep should change code, not commentary.

Verification

flake8  (all 44 changed files):  0 findings
isort   --check-only:            clean
black   --check:                 44 files unchanged
AST parse:                       all 44 files OK

knowledge/backends/ + api/desktop_control_lock_test.py
  this branch: 38 failed, 63 passed
  baseline:    38 failed, 63 passed     ← byte-identical

Those 38 are pre-existing chromadb-unavailable failures, present unmodified on Dev_new_gui.

Model Used

Claude Opus 5 (1M context)

Closes #12726

[github-actions]

✅ SSOT Configuration Compliance: Passing

🎉 No hardcoded values detected that have SSOT config equivalents!