refactor: Co-locate server artifacts under apps/server/

Move drizzle/, dist/, and coverage/ into apps/server/ so all
server-specific artifacts live alongside the source they belong to.

- git mv drizzle/ → apps/server/drizzle/
- drizzle.config.ts: out → ./apps/server/drizzle
- tsconfig.json: outDir → ./apps/server/dist, exclude drizzle dir
- package.json: main/bin/clean point to apps/server/dist/
- vitest.config.ts: reportsDirectory → ./apps/server/coverage
- .gitignore: add coverage/ entry
- ensure-schema.ts: update getMigrationsPath() for new layout
- docs/database-migrations.md: update drizzle/ references

apps/server/drizzle/0002_bumpy_killraven.sql

@@ -0,0 +1,12 @@
+CREATE TABLE `pages` (
+	`id` text PRIMARY KEY NOT NULL,
+	`initiative_id` text NOT NULL,
+	`parent_page_id` text,
+	`title` text NOT NULL,
+	`content` text,
+	`sort_order` integer DEFAULT 0 NOT NULL,
+	`created_at` integer NOT NULL,
+	`updated_at` integer NOT NULL,
+	FOREIGN KEY (`initiative_id`) REFERENCES `initiatives`(`id`) ON UPDATE no action ON DELETE cascade,
+	FOREIGN KEY (`parent_page_id`) REFERENCES `pages`(`id`) ON UPDATE no action ON DELETE cascade
+);