Fix atomic Linux host updates

[gitcommit90]

Outcome

Fixes the 0.0.11 Linux host updater's ProtectSystem=strict namespace so verified releases can atomically replace and roll back runtime files and systemd units. Releases this corrective desktop/host build as 0.0.12.

Changes

• apply runtime files, release symlink, units, restart, HTTP health gate, and rollback in one bounded transient root transaction
• safely bridge the old updater namespace, terminating only the exact validated legacy updater PID after a delegated rollback
• grant future updater units access to the required parent trees for atomic rename/removal
• create the LXC state and cache roots before systemd constructs the service namespace
• bump version, channel-image pins, changelog, and focused source contracts

Verification

• npm run typecheck
• npm run build
• npm test — 117/117 native-world; 96 passed, 1 documented Chrome-only skip
• npm run test:onboarding-browser — 20/20
• npm run test:brief-browser — 37/37
• node --test test/site.mjs — 5/5
• bash -n site/public/*.sh
• git diff --check
• disposable systemd fixture: untouched 0.0.10 updater unit upgraded to candidate 0.0.12; service HTTP healthy; /var/lib/1helm inode preserved
• disposable systemd rollback fixture: deliberately unhealthy candidate restored exact 0.0.10, restored its host contract, became HTTP healthy, preserved state inode, and retained a visible rollback-proven error

Signed-off-by: Joseph Yaksich gitcommit90@users.noreply.github.com