feat(ggplot2): implement pie-portfolio-interactive (#7774)

## Implementation: `pie-portfolio-interactive` - r/ggplot2

Implements the **r/ggplot2** version of `pie-portfolio-interactive`.

**File:** `plots/pie-portfolio-interactive/implementations/r/ggplot2.R`

**Parent Issue:** #3754

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:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/26527356861)*

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Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>

Author: github-actions[bot]

plots/pie-portfolio-interactive/implementations/r/ggplot2.R

@@ -0,0 +1,158 @@
+#' anyplot.ai
+#' pie-portfolio-interactive: Interactive Portfolio Allocation Chart
+#' Library: ggplot2 3.5.1 | R 4.4.1
+#' Quality: 86/100 | Created: 2026-05-27
+
+library(ggplot2)
+library(dplyr)
+library(ragg)
+
+# Theme tokens
+THEME       <- Sys.getenv("ANYPLOT_THEME", "light")
+PAGE_BG     <- if (THEME == "light") "#FAF8F1" else "#1A1A17"
+ELEVATED_BG <- if (THEME == "light") "#FFFDF6" else "#242420"
+INK         <- if (THEME == "light") "#1A1A17" else "#F0EFE8"
+INK_SOFT    <- if (THEME == "light") "#4A4A44" else "#B8B7B0"
+INK_MUTED   <- if (THEME == "light") "#6B6A63" else "#A8A79F"
+
+ANYPLOT_PALETTE <- c(
+  "#009E73",  # 1 — Equities (brand green)
+  "#C475FD",  # 2 — Fixed Income (lavender)
+  "#4467A3",  # 3 — Alternatives (blue)
+  "#BD8233"   # 4 — Cash (ochre)
+)
+
+# Portfolio holdings ordered by asset class
+cat_levels <- c("Equities", "Fixed Income", "Alternatives", "Cash")
+cat_colors <- setNames(ANYPLOT_PALETTE, cat_levels)
+
+holdings <- data.frame(
+  holding  = c(
+    "US Large Cap", "Intl Developed", "Emerging Mkts", "US Small Cap",
+    "US Treasuries", "Inv Grade Corp", "High Yield",
+    "Real Estate", "Commodities",
+    "Money Market"
+  ),
+  category = factor(c(
+    rep("Equities", 4),
+    rep("Fixed Income", 3),
+    rep("Alternatives", 2),
+    "Cash"
+  ), levels = cat_levels),
+  weight   = c(20, 18, 12, 5, 12, 10, 8, 6, 4, 5),
+  stringsAsFactors = FALSE
+)
+
+# Pre-compute angular midpoints and absolute dollar values (assumes $1M portfolio)
+holdings <- holdings |>
+  arrange(category) |>
+  mutate(
+    cum_end   = cumsum(weight),
+    cum_start = lag(cum_end, default = 0),
+    midpoint  = (cum_start + cum_end) / 2,
+    dollar    = paste0("$", weight * 10, "k")
+  )
+
+# Asset class summary for the inner ring
+categories <- holdings |>
+  group_by(category) |>
+  summarise(weight = sum(weight), .groups = "drop") |>
+  mutate(
+    cum_end   = cumsum(weight),
+    cum_start = lag(cum_end, default = 0),
+    midpoint  = (cum_start + cum_end) / 2
+  )
+
+# Title sizing (scale down only if longer than 67-char baseline)
+title_str  <- "pie-portfolio-interactive · r · ggplot2 · anyplot.ai"
+n_chars    <- nchar(title_str)
+ratio      <- if (n_chars > 67) 67 / n_chars else 1.0
+title_size <- max(8, round(12 * ratio))
+
+# Double-donut: inner ring = asset classes, outer ring = individual holdings
+p <- ggplot() +
+  # Outer ring: individual holdings
+  geom_col(
+    data      = holdings,
+    aes(x = 3.2, y = weight, fill = category),
+    width     = 1.0,
+    color     = "white",
+    linewidth = 0.5
+  ) +
+  # Inner ring: asset class summary
+  geom_col(
+    data      = categories,
+    aes(x = 2.0, y = weight, fill = category),
+    width     = 0.9,
+    color     = "white",
+    linewidth = 1.0
+  ) +
+  # Inner ring labels (skip Cash at 5% — too small)
+  geom_text(
+    data       = filter(categories, weight >= 8),
+    aes(x = 2.0, y = midpoint,
+        label  = paste0(gsub(" ", "\n", as.character(category)), "\n", weight, "%")),
+    color      = "white",
+    size       = 3.5,
+    fontface   = "bold",
+    lineheight = 0.75
+  ) +
+  # Outer ring labels: placed outside the ring at x=4.0 using INK so text
+  # always lands on PAGE_BG and remains readable in both light and dark themes.
+  # Shows holding name, percentage, and absolute value (assumes $1M portfolio).
+  # Only segments >= 10% are labeled to avoid crowding.
+  geom_text(
+    data       = filter(holdings, weight >= 10),
+    aes(x = 4.0, y = midpoint,
+        label  = paste0(holding, "\n", weight, "% · ", dollar)),
+    color      = INK,
+    size       = 2.6,
+    fontface   = "bold",
+    lineheight = 0.85
+  ) +
+  coord_polar(theta = "y", start = 0, clip = "off") +
+  xlim(c(0.7, 5.0)) +
+  scale_fill_manual(
+    values = cat_colors,
+    name   = "Asset Class"
+  ) +
+  labs(
+    title    = title_str,
+    subtitle = "Model Portfolio ($1M) · 10 Holdings · Inner ring: asset class  |  Outer ring: individual holding"
+  ) +
+  theme_void(base_size = 8) +
+  theme(
+    plot.background   = element_rect(fill = PAGE_BG, color = PAGE_BG),
+    panel.background  = element_rect(fill = PAGE_BG, color = NA),
+    plot.title        = element_text(
+      color  = INK,
+      size   = title_size,
+      hjust  = 0.5,
+      face   = "bold",
+      margin = margin(t = 16, b = 4)
+    ),
+    plot.subtitle     = element_text(
+      color  = INK_MUTED,
+      size   = 7,
+      hjust  = 0.5,
+      margin = margin(b = 8)
+    ),
+    legend.text       = element_text(color = INK_SOFT, size = 8),
+    legend.title      = element_text(color = INK, size = 10, face = "bold"),
+    legend.background = element_rect(fill = ELEVATED_BG, color = INK_SOFT, linewidth = 0.3),
+    legend.key.size   = unit(0.45, "cm"),
+    legend.position   = "bottom",
+    legend.direction  = "horizontal",
+    plot.margin       = margin(10, 40, 20, 40)
+  )
+
+# Save — square canvas: 2400 x 2400 px (6 in x 400 dpi)
+ggsave(
+  filename = sprintf("plot-%s.png", THEME),
+  plot     = p,
+  device   = ragg::agg_png,
+  width    = 6,
+  height   = 6,
+  units    = "in",
+  dpi      = 400
+)