feat: add SeekDB vector database support for knowledge bases

[Copilot]

概述 / Overview

Adds OceanBase SeekDB as a vector database option for knowledge bases. Fixed embedded mode initialization to auto-create database when specifying custom database names.

Core Changes

• SeekDB adapter (pkg/vector/vdbs/seekdb.py): Implements VectorDatabase interface with HNSW indexing, cosine similarity, async operations
• Database auto-creation: Embedded mode now creates the database if it doesn't exist before connecting
• Unit tests: 5 comprehensive tests covering all adapter operations

Configuration

vdb:
  use: seekdb
  seekdb:
    mode: embedded  # or 'server'
    path: './data/seekdb'
    database: 'langbot'

Platform Support

Mode	Linux	macOS	Windows
Embedded	✅	❌	❌
Server	✅	⚠️ #36	⚠️
Remote	✅	✅	✅

更改前后对比截图 / Screenshots

N/A - Backend feature

检查清单 / Checklist

PR 作者完成 / For PR author

• 阅读仓库贡献指引了吗？ / Have you read the contribution guide?
• 与项目所有者沟通过了吗？ / Have you communicated with the project maintainer?
• 我确定已自行测试所作的更改，确保功能符合预期。 / I have tested the changes and ensured they work as expected.

项目维护者完成 / For project maintainer

• 相关 issues 链接了吗？ / Have you linked the related issues?
• 配置项写好了吗？迁移写好了吗？生效了吗？ / Have you written the configuration items? Have you written the migration? Has it taken effect?
• 依赖加到 pyproject.toml 和 core/bootutils/deps.py 了吗 / Have you added the dependencies to pyproject.toml and core/bootutils/deps.py?
• 文档编写了吗？ / Have you written the documentation?

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• openwebapi.oceanbase.com
  • Triggering command: .venv/bin/python .venv/bin/python /tmp/test_seekdb.py (dns block)
  • Triggering command: `.venv/bin/python .venv/bin/python -c
    import pyseekdb
    from pyseekdb import HNSWConfiguration
    import tempfile
    import os

with tempfile.TemporaryDirectory() as tmpdir:
db_path = os.path.join(tmpdir, 'seekdb_test')

# Try creating client with just path
print('Testing with defaul` (dns block)

• Triggering command: .venv/bin/python .venv/bin/python /tmp/test_seekdb_final.py (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)