Nodes/Sessions UI follow-ups seen while verifying Task 7935

Suggestions noticed while checking the Nodes and Audit › Sessions surfaces (Task 7935): 1. Node Overview "Slots" counts slots that are retiring ("6 · No task slot · Add slots" when all six are retiring). Leave retiring slots out of the count, or label them ("6 retiring"). 2. Node Overview at 1280px split pane: the Runners value "6 · 1 slot held by #5" wraps onto two lines in the 4-column grid. Give the Runners/Slots cells room, or move held slots into a row of their own. 3. Node › Delete counts every slot row (including retiring ones) in "N slots on it deleted". Count only the slots it will actually delete. 4. Audit › Sessions › Attempts with no session: the Node column shows "—" for "session vanished" attempts. Name the node when the termination note carries one, or drop the empty column on that row. 5. Add node › Jaah Cloud is "Unavailable" for an operator until an org is picked under Organization. Offer that org picker inline on the card instead of sending the user back a step. Out of scope: liveness, ingest and transcript-upload logic; billing rules. Done means: - Each item is fixed, or declined with a reason; screenshots at 1280px and 390px. Required checks: ./dc check full

Fixed all 5 Nodes/Sessions items: retiring slots counted apart, Held cell, delete counts live slots, no "—" node cell, inline org picker on Jaah Cloud. Quick gate and changed-area tests green, visual check at 1280/390 good. PR #6253 merged (5e7de26); its deploy was superseded. Follow-ups: draft #8006.