feat(editor): allow date picker to navigate back to year 1000 (#14942)

Fixes #14935

## Summary

The date picker had a hardcoded `_minYear = 1970` in
[`date-picker.ts`](blocksuite/affine/components/src/date-picker/date-picker.ts),
which prevented users from selecting dates earlier than 1970. This
blocked legitimate use cases like historical and genealogical research
(see the reporter's comment on #14935).

## Fix

Lower the date picker's `_minYear` from `1970` to `1000`. The underlying
storage is just a `zod.number()` (Unix timestamp in ms), which supports
negative values, so no data-layer or backend changes are required — this
is a UI-only constraint relaxation.

## Demo

<img width="2044" height="1250" alt="image"
src="https://github.com/user-attachments/assets/4b25b333-89c4-48e6-9f91-81781d680200"
/>

## Test plan

- [x] Insert a database in a doc → add a Date column
- [x] Click a date cell → open the picker → click the year label →
navigate back through decades
- [x] Confirm the calendar reaches years well before 1970 (verified at
May 1805)
- [x] Confirm the calendar correctly renders weekdays for historical
dates
- [x] Confirm picking a modern date still works as before

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Date picker now allows selecting dates from year 1000 onward,
expanding historical date coverage.

* **Bug Fixes**
* Navigation (month switches and keyboard arrows) now keeps the
selection cursor within the allowed year range, preventing out-of-range
jumps.

[![Review Change
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