Chart starts at GitHub account creation date, not first actual contribution

[2u841r]

Problem

The chart's timeline starts at the user's GitHub account createdAt date (src/lib/cache.ts, monthlyWindows(createdAt, now)), not at the date of their first actual contribution.

For accounts created well before real activity began (e.g. signed up 2021, started actually committing/contributing in 2023), this produces a long flat/empty stretch at the start of the chart instead of the chart beginning where activity actually starts.

Suggested fix

Either:

• Trim leading empty months from the rendered chart (skip months before the first non-zero contribution), or
• Detect first real contribution date (e.g. from the earliest non-empty month in the GraphQL data) and use that as the window start instead of account createdAt.

Where to look

• src/lib/cache.ts around line 207-208 (createdAt / monthlyWindows)

[2u841r]

Additional idea: keep account-creation as the default start, but let users override the visible range explicitly, e.g. `?start=2023-01` / `?end=2024-01` (or just `?start=`) on both the chart page and the `/embed/` SVG route. That solves this issue's flat-years problem directly (user sets their own real start date) and also gives a general date-range feature for free.

[peetzweg]

That is a great idea, thanks for the suggestions. Will get to it this week. 👍