fix(fleet-view): clip sidebar entries to a glanceable headline

[ecloin]

Problem

The captain sidebar rendered every entry's full backlog title (bin/fm-fleet-view.sh, def short). In a real home a backlog title is a body rather than a label, so the first live render put a ~2400-character status dump - pull request verdicts, finding lists, file paths - into one NEEDS YOU headline, filled the whole 40-column pane, and pushed the second needs-you item off screen.

Reproduced against the pre-fix renderer with the new test: a single headline rendered at 471 characters.

Change

• An entry headline is the work item number plus the first sentence of its title (up to the first ., ;, or newline), clipped to a codepoint-aware TITLE_CAP, closed with a single … whenever anything was dropped.
• The assembled headline is bounded again by HEADLINE_CAP (about two wrapped lines at the default pane width), so N entries always cost about N * 3 lines regardless of what the headline was built from.
• The same clipping covers every section - NEEDS YOU, IN FLIGHT, WAITING, DONE TODAY - so no section renders a note body, verdict list, findings, or raw worker report.
• The action line stays deliberately outside every budget. A pull request URL or review command goes out whole and soft-wraps, because a truncated command is worse to receive than a long one.
• Decision and declared-wait notes moved from ad-hoc cap(90) / cap(70) onto the shared NOTE_CAP constant.

The change is confined to the sidebar classifier. bin/fm-fleet-snapshot.sh is untouched, so its read-only guarantee is unaffected.

Tests

Two new fixtures in tests/fm-fleet-view.test.sh, both driven by a multi-hundred-character title modeled on the live reproduction:

• test_long_title_stays_glanceable - asserts the headline stays within the cap, that the verdict body / finding list / file paths never reach the pane, that the second needs-you entry survives, and that both a full PR URL and a review command render unclipped.
• test_long_title_clipping_covers_every_section - asserts in-flight, waiting, and done-today entries clip identically.

Both fail against the pre-fix renderer and pass after.

Verification

• bash tests/fm-fleet-view.test.sh - 12/12 ok.
• bash tests/fm-fleet-snapshot-view.test.sh - no failures.
• bin/fm-doc-audience-check.sh - ok, surfaces=68 local_links=235.
• --wide and --json output diffed byte-for-byte before and after against a long-title fixture home: identical, and --wide still carries the full title.
• bin/fm-lint.sh could not run in this environment: ShellCheck is not installed, and the linter correctly refuses to run under any version other than the pinned 0.11.0. bash -n is clean on both changed scripts; CI owns the ShellCheck gate.

Docs

docs/fleet-view.md gains a "What an entry looks like" section describing the clipping contract, the never-clipped action line, and the fact that --wide / --json are unaffected.

[ecloin]

CI: 11 passed, 2 failed.

• PR must be raised via no-mistakes - fails by design: this was dispatched as a direct-PR task, so the no-mistakes pipeline was deliberately not run. Every PR on this fork (feat(brief): generate the since-last-review marker contract #1, feat(fleet-view): add the narrow needs-you-first captain sidebar #2, feat(herdr): name each spawned agent after its task #3) shows the same red.
• Behavior tests (Herdr) - unrelated to this change. This lane installs and drives real Herdr; nothing here touches Herdr, spawning, or backends - the diff is confined to the sidebar classifier in bin/fm-fleet-view.sh plus its colocated tests and docs/fleet-view.md. The same lane failed on feat(herdr): name each spawned agent after its task #3 and passed on feat(brief): generate the since-last-review marker contract #1 and feat(fleet-view): add the narrow needs-you-first captain sidebar #2, so it is flaky in this fork.

Everything that covers this change is green, including Lint shell scripts (ShellCheck parity, which could not run locally), Test coverage guard, all six portable behavior shards, Stock macOS Bash snapshot compatibility, and Repo invariants.