fix/duration-filters

[alanpeixinho]

What it is

Fixes duration filter handling in the dashboard and API:

• Duration filters showing 0 filter card #428: 0 is not treated as an active duration filter (no chip, not persisted, not sent). Duration inputs show 0 correctly (?? instead of ||). Clearing a duration field removes it from filter state.
• wrong param parse on build duration #2126: Non-zero duration filters work from URL state and query params: minified URL keys parse as numbers, Zod coerces duration values safely, API mapping only sends active durations, and the backend no
  longer truncates multi-digit values (e.g. 3600 → 3) when filters come from the query string.

Closes #428
Closes #2126

How to test

1. Open a tree view with duration filters (build / boot / test).
2. Set min or max to 0 → no duration chip; other filters unchanged.
3. Set a non-zero duration (e.g. build min 120) → chip appears; results respect the filter.
4. Reload or share the URL with duration in df|… → chip and filter still apply.
5. (API) Request with filter_duration_[lte]=3600 → results match 3600, not 3.