Add TEJ provider for Taiwan market data

[Han860207]

Description

Summary

Add TEJ (Taiwan Economic Journal) as a new data provider for the OpenBB Platform.
TEJ primarily provides market data for companies listed on the Taiwan Stock Exchange (TWSE) and Taipei Exchange (TPEx).

New Endpoints

Endpoint	Standard Model	TEJ Table
obb.equity.price.historical	[EquityHistorical]	TWN/APRCD
obb.equity.fundamental.balance	[BalanceSheet]	TWN/AINVFINA
obb.equity.fundamental.income	[IncomeStatement]	TWN/AINVFINA
obb.equity.fundamental.cash	[CashFlowStatement]	TWN/AINVFINA

Dependencies

• tejapi (^0.1.31) — TEJ official Python API client

As this is a new community provider, please advise if any additional updates to extension/provider lists or CI workflows are needed.

---

How has this been tested?

• load .env file with setting OPENBB_TEJ_API_KEY=<API_KEY>
• Unit tests via fetcher.test() for all 4 fetchers ([tests/test_tej_fetchers.py])
• Manual verification via Python interface with symbol "2330" (TSMC)
• Verified field mapping completeness for Balance Sheet, Income Statement, and Cash Flow Statement
• All financial statements fetch single-quarter data (no="Q") from TWN/AINVFINA

Test command

pytest openbb_platform/providers/tej/tests/test_tej_fetchers.py -v

[CLAassistant]

All committers have signed the CLA.

[deeleeramone]

Hi, thanks for the PR. The code looks great, but unfortunately we will not be able to host and maintain this provider extension because proprietary vendor APIs require active subscriptions for complete and maintainable implementations.

OpenBB and the maintainers will not be purchasing subscriptions in order to test, maintain, and utilize this provider. The circumstances are not a comment on code quality, viability, or usefulness of the proposed implementation. We do appreciate that you took the time to build this and share it back.

I propose that you move this extension into a repository that you own and maintain, publishing the package to PyPI directly from there as a standalone (I recommend wrapping as many endpoints as possible). After being made available publicly, please share the repository and package details here - https://github.com/OpenBB-finance/awesome-openbb - under a new section, ODP Provider Extensions.