release 0.3.20 plan: the one-off cards exception on PC 1; the signed cards job kind for 0.3.20

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/plans/release-0.3.20.md

@@ -323,3 +323,5 @@ c18-1 (RTX 3070 pod, wiped datadir, from 08:51:50Z; the Mac's reboot cut the for
 - Two app faults for the reliability lane's rules, both 0.3.20's app (main): (1) engine.rs:3032, the runner's --stop-miners hold is not released while a following job runs (the resume fires only when job_hold is set and no job holds the miners), so a read-only watch job kept both cards off for three minutes; (2) orphan igneum-miner.exe processes the app no longer tracks (two alive under --stop-miners with their rows at pid 0, one after) hammer the node's template RPC beside the tracked miners, part of why PC 1's template calls ran past 5 s. Sizing of the orphan-kill for an app-only 0.3.20: below.
 - The fleet's prover-identity finding was withdrawn (no box shares a key; the "shared" hashes were a carrier block's record list); no migration. The kit rule stands on another ground: `igneum-miner key-hash <label>` is a pure function of the label, so the 0.3.20 kit seeds the identity from the box, keeps the hash on the registry row, refuses a duplicate.
 - The node lane's IBD-end read (ca3-v4-node d49c71d0): the weight-table cache (64 tables, cleared past that) made every 2,000-body IBD batch walk the window again (359,709 tables for 5,335 checkpoints, 968 s); fix on release-0.3.20-node: WEIGHT_TABLE_CACHE = 1,024, oldest-first eviction, never a clear, a unit test; bodies 16,592 s is thread time behind the finality state lock, not CPU; the next fresh join on the pod should read 60 to 70 minutes.
+
+**Main (11:5x UK):** a one-off exception to the 6 October rule, the project lead's word ("you will have to fix it"): exactly one POST to /api/cards on PC 1 from the Intel lane's scratch script (not in the tree), the 5090 and the 9070 XT to 2 identities and the Arc off; the engine restarts the workers on the change. The permanent path is the reliability lane's signed `cards` job kind (per-card enabled, identities, power_pct, through the app's own card path, read back), which replaces any runner option: 0.3.20.