Node console polish for unsupported features (Linux

Found by the Linux matrix sweep (Task 11113, report "Console notes") on dev, 2026-10-29, while checking new Ubuntu/Amazon Linux nodes in the dev console. Three small UI faults on the node pages: 1. **A stale "needs rootless Docker" sentence.** Observed: a host keeps showing "needs rootless Docker, which this node doesn't have yet" for up to 10 minutes after it is already running a vnode. Cause: `apps/jaahd/host_platform/__init__.py:113` `HOST_FEATURES_TTL_S = 600.0` caches the feature probe. Fix: invalidate the features cache when the probed state can have changed (rootless Docker install converges, vnode start), or re-probe a negative result on a short TTL, so the node's `unsupported` clears within one heartbeat of the feature appearing. 2. **The MicroVM tab shows sizing when MicroVM is unavailable.** Observed: on a node whose `unsupported.microvm` is set (arm64, older releases), the tab still shows the Size editor and a "Larger than this host" warning. Cause: `apps/web/src/components/microvm/NodeMicrovmTab.tsx:555` renders the `Size` DetailSection without checking `node.unsupported?.microvm`. Fix: when MicroVM is unavailable and off, hide the Size section (and its warning) and show only the reason sentence. 3. **The OS label wraps mid-label.** Observed: the node Overview shows "Amazon Linux 2027 ·" on one line and "x86" on the next. Cause: `apps/web/src/pages/NodeDetailPage.tsx:1440` renders `nodeOsArchLabel(...)` with no nowrap. Fix: keep the label on one line (nowrap, plus ellipsis with the full label on `title` if it overflows), as the Nodes list does with `OS_SLOT`. Out of scope: do not change which features a node supports, the `unsupported` sentences' wording, MicroVM sizing logic, or the Nodes list columns. No new settings. Done means: - (1) A jaahd unit test shows that a feature becoming available is reported on the next heartbeat after the change, not after 600 s. Oracle: the test, plus a dev node whose rootless-Docker reason clears within about 1 minute of a vnode starting. - (2) A web test: with `unsupported.microvm` set and MicroVM off, `node-microvm-sizing` is absent and the reason is shown. Oracle: the vitest test, plus a dev arm64 node's MicroVM tab, checked visually. - (3) A web test or Playwright check at 1280 px: the Amazon Linux 2027 · x86 label renders on one line. Oracle: a screenshot on dev. - `./dc check quick` green; merge lane full gate green; Jaah Deploy to dev succeeds.

Fixed all 3 node-page faults (#7337) plus a read-only MicroVM reason found in the visual check (#7341). Both merged on green full gate; Jaah Deploy to dev succeeded for both; dev visual check done. No arm64/AL2027 node on dev, so live checks used a doctored payload. Memory: none applied.