add datetime-local to RFC 3339 handling in BaseInput

[steven-klein]

What this does

• handles read/write v-model transformation when BaseInput is type=datetime-local

Note

[email protected] ships with custom v-model modifiers and a defineModel macro, which might be a cleaner long term path, but I don't expect many more of these kinds of two-way transforms being necessary, so I'd rather ship something out now, and look more closely at defineModel + useModal before reaching for them.

[steven-klein]

@DavidLarsKetch I believe this will handle datetime-local inputs. npm install @xy-planning-network/trees@dev if you want to do a quick test.

[DavidLarsKetch]

Haven't been able to force any bugs, so the transforming is working well. If we opt to not go with a custom component then 👍 on merging this PR.

[steven-klein]

closing in favor of #61