feat(cli): pin plan chip above the composer + dedup the inline checklist

[cukas]

Move the one-line plan-progress chip (◈ STATE · PLAN id · Step n/m · bar · % · current step) out of the top ChromeBar into a new PlanChip pinned directly above the chat input, so plan state is glanceable at the point of focus instead of buried at the top of the dynamic region.

• Extract PlanChip (app-views); render it in BottomChromeSection above the composer; drop the chip + its four plan props from ChromeBar.
• Suppress the redundant inline plan-step checklist while a plan shows (TodoList planActive), keyed on the chip's OWN visibility predicate (planChipVisible = buildPlanChromeSummary(...).visible) so the two surfaces never drift — incl. the post-done retain window. Live (non-plan) todos always render (todos-marker forces source:'live').
• Reserve the chip's single row in the bottom-chrome budget (estimateBottomChromeExtraRows hasPlanChip); wrap="truncate-end" pins the chip to one row so a long line can't wrap past that reservation.
• Drop the auto-open rail takeover idea; Ctrl+G stays the on-demand rail.

Bundled pre-existing fix (root cause of the above budget being effective): a KERN codegen precedence bug compiled (cond ? a : b) + x as (cond) ? a : (b + x). In estimateVisibleBlockBudget this made chat mode IGNORE all overlayReservedRows (pickers/images/spinner/question cards/chip), over-budgeting the transcript; it also hit buildTerminalReplaySnapshot's lowerChromeRows. Worked around by splitting the bare ternary into its own let (KERN-GAP notes left at both sites for the compiler team).

Validated: kern:compile + typecheck clean; full suite 3213 passing (only the pre-existing, unrelated agy-probe-e2e fails). +2 regression tests lock the chip-row budget. Reviewed twice by the 6-engine agon panel; all findings addressed or verified non-issues.

⚔️ Forged by Agon