logs/journal: low-severity batch (dead source chip, ts-sort, dead LIMIT_MAX, stale docstrings)

[thinmintdev]

What's broken (low-severity batch)

Cosmetic / low-impact log/journal defects found during the 2026-06-14 audit. Batched; split out if any is picked up individually.

• Dead source chip — JournalEntry.source is hardcoded Literal["hal0"]; the merged/hal0 footer filter is identical (ui/src/dash/chrome.jsx, src/hal0/api/routes/journal.py).
• Unstable ordering — the journal UI and journal.py sort by the ts string instead of the monotonic id, giving unstable ordering for same-millisecond events (ui/src/dash/chrome.jsx, extras.jsx).
• Dead headroom — _LIMIT_MAX=1000 on a 500-deep ring is unreachable, and its comment is wrong (src/hal0/api/routes/events.py).
• Stale docstrings — several modules say "Vue dashboard" (it's React) and claim slot logs come via /api/logs when the UI actually uses /api/slots/{name}/logs/stream (health.py, journal.py, events/journal docstrings).

Acceptance criteria

• Journal sorts by id, not ts string
• Source chip either does something or is removed
• _LIMIT_MAX comment corrected (or made meaningful once durable store lands)
• Stale Vue//api/logs docstrings corrected

Triaged 2026-06-14 by audit agent (live-verified on CT105). Part of the Activity/Audit store epic — see docs/superpowers/specs/2026-06-14-activity-audit-store-design.md.
Severity: LOW. Deferred.