whatif: live data refresh, inflation-adjusted spending, legend fix

Three follow-ups to the actualbudget integration:

**Always-fresh autofill.** Drop the one-shot `*AutoFilled` boolean
gates; replace with `nwUserEdited` / `spendingUserEdited` flags. Until
the user types into either field, every refetch (mount, window
focus) updates the form value. Once they edit, we leave it alone. A
small ↻ button next to each anchor input flips the edited flag back
off so the user can re-snap to live data on demand. React Query
configured with staleTime=0 + refetchOnMount='always' +
refetchOnWindowFocus=true so the cache never serves stale numbers.
NW provenance shows the snapshot date.

**Inflation-adjusted spending.** Backend now revalues each trailing
month's nominal pence forward to today's £ using monthly compounding
of `inflation_pct` (default 0.03 ≈ UK CPI 2024-26). Headline
`total_gbp` is the real-£ figure — matches the simulator's
real-GBP convention. Response also includes `nominal_total_gbp` and
`inflation_pct` for transparency. New /spending/annual?inflation_pct=
override param. 10/10 actualbudget tests pass.

**FanChart legend.** The bottom-anchored legend was overlapping the
x-axis label. Moved to top: 8 with itemGap=18 + type=scroll for
narrow viewports; bumped grid top→48 / bottom→56 + xAxis nameGap→28
so nothing collides.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

fire_planner/api/spending.py

@@ -41,6 +41,15 @@ async def annual_spending(
             f"from the headline total. Defaults to: {','.join(DEFAULT_EXCLUDE_GROUPS)}."
         ),
     ),
+    inflation_pct: float = Query(
+        default=0.03, ge=0.0, le=0.30,
+        description=(
+            "Annual inflation rate used to revalue past months' spending "
+            "into today's £. The simulator runs in real GBP, so the headline "
+            "`total_gbp` is the inflation-adjusted (real) figure. Default ≈ "
+            "UK CPI 2024-26."
+        ),
+    ),
 ) -> AnnualSpending:
     excluded = (
         [g.strip() for g in exclude.split(",") if g.strip()]
@@ -48,9 +57,10 @@ async def annual_spending(
         else list(DEFAULT_EXCLUDE_GROUPS)
     )
     try:
-        spends, total_gbp = await fetch_trailing_spending(
+        spends, nominal_gbp, real_gbp = await fetch_trailing_spending(
             months=months,
             exclude_groups=frozenset(excluded),
+            annual_inflation_pct=inflation_pct,
         )
     except Exception as e:
         log.exception("actualbudget unreachable")
@@ -93,8 +103,10 @@ async def annual_spending(
         window_start=monthly[0].month,
         window_end=monthly[-1].month,
         excluded_groups=excluded,
-        total_gbp=total_gbp,
+        total_gbp=real_gbp,
+        nominal_total_gbp=nominal_gbp,
         raw_total_gbp=raw_total_gbp,
+        inflation_pct=Decimal(str(inflation_pct)),
         by_group_total_gbp=by_group_gbp,
         monthly=monthly,
     )