feat(fleet-view): add the narrow needs-you-first captain sidebar

[ecloin]

What this changes

bin/fm-fleet-view.sh renders one wide Markdown table set today, which reads well in a full-width terminal but not in the narrow split pane a captain keeps open beside a session.

This makes the captain sidebar the default rendering:

⚓ FLEET · 19:40 · 7 tasks · 3 need you
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
NEEDS YOU (3)
● PR #1905 pane-naming — checks green,
  awaiting merge word
  ↳ https://github.com/kunchenguid/firstmate/pull/1905
● 3412 contracts — decision: pick REST
  or gRPC for the sync endpoint
● 7002 local ready — ready to review on
  your local copy
  ↳ bin/fm-review-diff.sh 7002
IN FLIGHT (2)
◐ 3406 merge-strategy — working 1h
◐ 7003 dead worker — working 14m
WAITING (2)
○ 2909 review scout — report ready,
  decisions open
○ 7001 pause task — upstream release
  lands Thursday
DONE TODAY (1)
✓ 3410 re-verify

• --watch [seconds] redraws on an interval (default 5s) and exits cleanly on interrupt.
• --wide keeps the previous Markdown tables; --json is unchanged.
• Entries that ask for something carry a copyable full PR URL or a runnable review command.
• Wording is captain-facing throughout: no internal state, monitoring, or runtime vocabulary.

Read-only

The view still consumes bin/fm-fleet-snapshot.sh --json rather than reparsing fleet state, so it inherits the snapshot's read-only guarantee: no session lock, no queue drain, no monitoring, nothing sent to a worker, and no writes under state/ or data/.
That is what makes it safe to leave redrawing beside a live session, and tests/fm-fleet-view.test.sh pins it by comparing every file in a fixture home - including modification times - across a render.

Snapshot additions

Two additive fields, both documented in the script header:

• paths.status_log.last_event_epoch / .age_seconds date the last status append, so a renderer can age a declared event without stat-ing state files itself.
• actions.review carries the per-task review command, which bin/fm-review-diff.sh already owns.

Notes

• Wrapping counts codepoints rather than bytes, because the section glyphs and the em dash are multibyte and a byte-counting wrap folds a 40-column pane several characters early. A test drives a long entry through a fixed-width render and fails if any line overruns.
• A copyable URL or command is never folded, so a double-click still selects all of it.
• A second mate earns a line only when it is actually holding something, since a persistent second mate idles by design.

Verification

• bin/fm-lint.sh clean (ShellCheck 0.11.0).
• bin/fm-doc-audience-check.sh clean; docs/fleet-view.md classified operator-current.
• bin/fm-test-run.sh --changed - 32 selected scripts, all passing.
• bin/fm-test-run.sh --family snapshot-bearings - 3/3 passing, including the existing bearings and snapshot coverage.
• The new width and read-only tests were each confirmed to fail when the behavior they cover is removed, so neither passes vacuously.