feat: implement project management features with cover images and planning sections

- Add ProjectsClient component for managing projects with a grid and list view.
- Introduce project cover image functionality and related fields in the database.
- Create a new table for project planning sections with RLS policies for user access.
- Update global styles for scrollbar customization.
- Enhance Next.js configuration for server actions with increased body size limit.
- Document new database migration for project planning assets.

docs/database/0003-project-planning-assets.md

@@ -0,0 +1,92 @@
+# 0003 - Project Planning Assets
+
+SQL file: `supabase/migrations/0003_add_project_planning_assets.sql`
+
+## Purpose
+
+This migration extends project management beyond task tracking.
+
+It adds:
+
+- Project cover image fields on `projects`
+- A private Supabase Storage bucket for uploaded project images
+- A structured `project_planning_sections` table for project planning categories
+
+## Project Image Fields
+
+The `projects` table receives:
+
+- `cover_image_path`: path of the uploaded file in the `project-assets` bucket
+- `cover_image_alt`: optional alt text for the cover image
+
+Images are uploaded from the user's computer, not saved as external image links.
+
+## Storage Bucket
+
+Bucket:
+
+- `project-assets`
+
+Configuration:
+
+- Private bucket
+- Max file size: 5 MB
+- Allowed MIME types:
+  - `image/jpeg`
+  - `image/png`
+  - `image/webp`
+  - `image/gif`
+
+Storage object paths must start with the authenticated user id:
+
+```txt
+<user_id>/projects/<project_id>/<file_name>
+```
+
+This keeps Storage RLS simple and user-scoped.
+
+## Planning Sections
+
+Table:
+
+- `project_planning_sections`
+
+Core fields:
+
+- `user_id`
+- `project_id`
+- `category`
+- `title`
+- `content`
+- `metadata`
+- `sort_order`
+
+Allowed categories:
+
+- `overview`
+- `problem`
+- `goal`
+- `audience`
+- `scope`
+- `design_system`
+- `color_palette`
+- `typography`
+- `assets`
+- `notes`
+
+## RLS
+
+RLS is enabled for `project_planning_sections`.
+
+Users can only select, insert, update, and delete their own planning sections.
+
+Storage policies allow users to select, upload, update, and delete only files under their own user id folder inside `project-assets`.
+
+## Execution
+
+Run after:
+
+1. `supabase/schema.sql`
+2. `supabase/migrations/0002_add_freelancer_os_core_tables.sql`
+
+After running this SQL in Supabase, add an execution record to `docs/database/query-log.md`.