Fix stale post-widen deck-reflow figures (90/144/1190px) across docs and tests, and split test_deck_groups.cpp's width-budget fixtures into a new file.

docs/PLAN.md

@@ -613,7 +613,9 @@ folded into the tracks below:
 - **Γ-F4** — there **is** an explicit loop enable, and it lives on the **chrome row**, not
   in a deck. W2-T2's scope grows accordingly — spec §6.4.
 - **Γ-F5** — MASTER's reserved slot is **one** cell. The 90 px headroom argument behind
-  that is spec §1.6 and governs every future control addition.
+  that is spec §1.6 and governs every future control addition. (**Moved afterwards:**
+  Γ-W3-T1 widened the row block, so §1.6's ledger is now 82 px — the ruling and its
+  purchasing power are unchanged, only the number.)
 - **Γ-F6** — **ship dynamic latency as ruled.** The `restartComponent(kLatencyChanged)`
   deactivate/reactivate the SDK mandates is accepted: *"the limiter will either be on or off
   on its instance, toggling during playback is not a use case."* No constant-latency
@@ -1083,9 +1085,9 @@ waveform band.
   Row 1's natural width fits the block **only after this track's `Band|Notch` move**: 1030
   today, +42 from W2-T1's PITCH/RATE, −92 here, = **980**. That is this track's fit assertion
   and W1-T4 deliberately left it open.
-- **The 90 px of remaining headroom is the budget for the life of this layout**, and one deck
+- **The 82 px of remaining headroom is the budget for the life of this layout**, and one deck
   cell is 60 px. **This is why MASTER's reserved slot is ONE cell** (Γ-F5, ruled): two would
-  spend 60 of the 90 up front on a control nobody has named, leaving 30 — which would freeze
+  spend 60 of the 82 up front on a control nobody has named, leaving 22 — which would freeze
   row 1 forever, since any later row-1 addition needs 60. Widening MASTER later costs the same
   60 it would cost now, and by then the trade is against a real control instead of a guess.
   **State this ledger where a future reader will hit it** — spec §1.6 is its home, and a