Task page polish found while documenting it

Found while photographing the task page (/tasks/:id) and New Task on prod for the docs (Task 6705): 1. The header status pill shows "☑ Done" while the Details tab's State field shows "✓ Done" for the same state; use one icon for a state everywhere. 2. A task with no feature shows "(other)" in its breadcrumb; show nothing (project › title) or a clear label instead of a parenthesised placeholder. 3. On an older task the Outcome shows a bare "merged PR ↗" link while newer tasks show "owner/name #n" with a state chip; render the legacy link in the same owner/name #n form, parsed from its URL. 4. The Activity tab's "Outcome reported" entry repeats the full outcome summary already on Details; collapse it to a line or a link to Details. Out of scope: the Tasks board list, task states and transitions, any API change beyond what item 3 needs (none expected). Done means: each item above is visible on /tasks/:id on a dev stack, with a screenshot per item in the report; `./dc check full` green.

Task page: one ✓ Done glyph, "No feature" crumb, legacy PR as owner/name #n + merged chip, one-line Activity outcome with Details link. Full gate green, visual check done per item; PR #5642 merged (deploy superseded). Follow-up draft #6726.