chore(deps): upgrade recharts 2 → 3 (T02 It5) (#82)

* chore(deps): upgrade recharts 2 → 3 with chart.tsx type migration

- recharts ^2.15.4 → ^3.8.1
- chart.tsx: replace ComponentProps<Tooltip> with TooltipContentProps,
  LegendProps pick with DefaultLegendContentProps pick, coerce dataKey
  to string for React key
- add smoke test for DashboardCharts render (3 assertions)
- ADR-005 written to docs/decisions/ (gitignored docs vault)

Supersedes Dependabot PR #78

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix(chart): use precomputed key var for tooltip item stability

CodeRabbit: item.dataKey can be undefined or Function in recharts 3,
causing duplicate/invalid React keys. Use the already-computed `key`
variable (nameKey || item.name || item.dataKey || 'value') instead.

Also remove invalid `language: typescript` from .coderabbit.yaml
code_generation.docstrings — not a valid enum value (docstrings disabled
anyway).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Emiya Kiritsugu <emiyakiritsugu3@users.noreply.github.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: EmiyaKiritsugu3

.coderabbit.yaml

@@ -11,4 +11,3 @@ reviews:
 code_generation:
   docstrings:
     enabled: false
-    language: typescript

package-lock.json

@@ -95,7 +95,7 @@
     "react-dom": "^18.3.1",
     "react-hook-form": "^7.72.1",
     "react-timer-hook": "^4.0.5",
-    "recharts": "^2.15.4",
+    "recharts": "^3.8.1",
     "tailwind-merge": "^2.6.1",
     "zod": "^3.25.76"
   },