Version 0.21.0

Version v0.20.3

cli: Fix `ipo_date` showing 1970 in IPO commands (#197)

## Summary

- `ipo_date` from the API is a YYYYMMDD string (e.g. `"20260511"`).
`fmt_date_opt` was parsing it as an integer `20260511`, then passing it
to `format_date` as Unix seconds, producing a bogus 1970 date
- Fixed `fmt_date_opt` to detect 8-digit and `YYYY-MM-DD` date strings
early and return them directly, before the timestamp parsing path
- Removed `"ipo_date"` from `TS_FIELDS` — it already has dedicated
handling in `transform_ipo_list_item`
- Fixed `wait_list_row` and `cmd_ipo_us_wait_listing` to use
`fmt_date_opt` instead of `fmt_ts` for `ipo_date`

## Affected commands

`ipo listed`, `ipo wait-listing`, `ipo calendar`, `ipo us-wait-listing`

## Test plan

- [x] `ipo listed` — HK and US dates show correctly (e.g. `2026-05-11`)
- [x] `ipo calendar` — `sub_date`, `sub_end_date`, `ipo_date` all
correct
- [x] `ipo wait-listing` — `ipo_date` correct

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

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