feat: phase 0 foundation — monorepo scaffold, backend, frontend, CI, docker

Establishes the skeleton every later phase builds on: Go+Gin API with
zap logging, /api/healthz, SQLite+goose runner; Vite+React18+TS strict+
Tailwind v4 frontend with bento-mono theme tokens; openapi.yaml driving
a generated TS client; oxlint with vendored anti-slop rules; GitHub CI;
multi-stage Dockerfile -> 33.6MB distroless image; docker compose up
serves the blank board.


Generated with [Devin](https://devin.ai)

Authored By: TDvorak <[email protected]>
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/internal/web/web.go

@@ -0,0 +1,41 @@
+// Package web serves the embedded frontend build (SPA with index.html
+// fallback). dist/ is populated by the frontend build in Docker/CI; the
+// committed .keep keeps //go:embed satisfied on a bare clone.
+package web
+
+import (
+	"embed"
+	"io/fs"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+)
+
+//go:embed all:dist
+var dist embed.FS
+
+// Register mounts the SPA on the router. Non-/api paths serve static files;
+// unknown paths fall back to index.html for client-side routing.
+func Register(r *gin.Engine) error {
+	sub, err := fs.Sub(dist, "dist")
+	if err != nil {
+		return err
+	}
+	fileServer := http.FileServer(http.FS(sub))
+
+	r.NoRoute(func(c *gin.Context) {
+		path := c.Request.URL.Path
+		if len(path) >= 4 && path[:4] == "/api" {
+			c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
+			return
+		}
+		if f, err := sub.Open(path[1:]); err == nil {
+			_ = f.Close()
+			fileServer.ServeHTTP(c.Writer, c.Request)
+			return
+		}
+		c.Request.URL.Path = "/"
+		fileServer.ServeHTTP(c.Writer, c.Request)
+	})
+	return nil
+}