docs(readme): declare fork status and document upstream sync workflow

GitHub does not allow retro-converting an existing repo into a fork
(fork relationship is only established via the Fork button at creation
time), so the relationship to upstream pondpilot/flowscope is recorded
explicitly in the README instead:

- Top-of-file Note: states this is a personal fork of pondpilot/flowscope
  with customizations (Trellis AI workflow, audit review page,
  derived-subquery JOIN fix, Cursor IDE platform support).
- New "Syncing with upstream" section: documents the git remote layout
  (origin = personal fork, upstream = pondpilot/flowscope with push
  intentionally disabled), the standard fetch/merge/push flow, and the
  one-shot `git sync-upstream` alias.

Repo metadata on GitHub also updated via gh repo edit:
- Topics: fork, sql-lineage, trellis, rust, wasm, cursor-ide
- Homepage: points to https://github.com/pondpilot/flowscope

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: wangliangbj01

README.md

@@ -1,5 +1,7 @@
 # FlowScope
 
+> **Note**: This is a personal fork of [`pondpilot/flowscope`](https://github.com/pondpilot/flowscope) maintained by [@cooker-code](https://github.com/cooker-code) with additional customizations (Trellis AI workflow integration, audit review page, derived-subquery JOIN fix, Cursor IDE platform support). Upstream is tracked via the `upstream` git remote and synced periodically; see [Syncing with upstream](#syncing-with-upstream) below.
+
 [![CI](https://github.com/pondpilot/flowscope/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/pondpilot/flowscope/actions/workflows/ci.yml)
 [![Docs](https://img.shields.io/badge/docs-available-brightgreen.svg)](docs/README.md)
 [![codecov](https://codecov.io/gh/pondpilot/flowscope/graph/badge.svg)](https://codecov.io/gh/pondpilot/flowscope)
@@ -206,6 +208,30 @@ See [CONTRIBUTING.md](CONTRIBUTING.md) for setup, testing expectations, and cont
 
 The core engine and packages are released under Apache-2.0. See [LICENSE](LICENSE) for details. The `app/` directory uses the O'Saasy License; see [app/LICENSE](app/LICENSE).
 
+## Syncing with upstream
+
+This fork tracks `pondpilot/flowscope` via the `upstream` git remote. To pull in upstream changes:
+
+```bash
+git fetch upstream
+git log --oneline master..upstream/master   # preview what's new
+git merge upstream/master                    # or: git rebase upstream/master
+git push origin master
+```
+
+If you set up a one-shot alias:
+
+```bash
+git config alias.sync-upstream '!git fetch upstream && git merge upstream/master && git push origin master'
+git sync-upstream
+```
+
+The `upstream` remote has its push URL intentionally disabled to prevent accidental pushes to `pondpilot/flowscope`. Restore it explicitly if you ever need to open a PR:
+
+```bash
+git remote set-url --push upstream https://github.com/pondpilot/flowscope.git
+```
+
 ---
 
 Part of the [PondPilot](https://github.com/pondpilot/pondpilot) project.