…-1708-clean

…range

Problem:
Timeline was showing wrong phase color (e.g., Käynnistys green instead of
Ehdotus red) when the visible date range contained no phase_start or
phase_end markers. This happened because:
1. createStartAndEndPoints blindly placed phase markers if their date
   mapped to a visible slot, ignoring whether the phase was actually
   valid/active during that time
2. The fallback logic in fillGaps iterated deadlines sequentially and
   picked the last phase_start before visible range, which was often
   the wrong phase

Solution:
Added three new helper functions:
- getSlotDate(): Computes actual calendar date for a timeline slot
- buildPhaseTimeline(): Pre-processes deadlines to build a map of each
  phase's effective start/end dates (earliest start, latest end)
- findActivePhaseAtDate(): Determines which phase is active at a given
  date by checking start <= date <= end

Key changes in createStartAndEndPoints:
- Compute visible date range from inputMonths
- Build phase timeline and filter to only phases that overlap with
  visible range AND have valid dates (start <= end)
- Skip phases with invalid date ordering (e.g., start > end)
- Skip individual deadlines whose dates fall outside visible range

Key changes in fillGaps:
- Replaced old sequential deadline iteration with proper phase lookup
- Uses findActivePhaseAtDate to find the correct active phase at
  visible start date, ensuring correct color is displayed

- Only apply 'first' rounded corners when phase actually starts (phase_start)
  or there's a real color transition (previous slot had different color)
- Only apply 'last' rounded corners when phase actually ends (phase_end)
  or there's a real color transition (next slot has different color)
- Phases continuing from before visible range (past_start_point) no longer
  get incorrect rounded left corners
- Phases continuing beyond visible range no longer get incorrect rounded
  right corners
- Fixed inner milestone width to use 100% for middle segments
- Added gap: 0 to timeline grid container

Bug: When a phase_end (e.g. Käynnistys K2) landed exactly on the first
visible week of the timeline, the has_endpoint_in_range flag was not
being set in the else branch of fillGaps() (for slots with 4+ keys).
This caused the code to incorrectly fall into the 'no endpoints in range'
special case, overwriting the entire timeline with the wrong phase color.

Fix: Set has_endpoint_in_range = true in both branches of the fillGaps
loop when a deadline_type array is detected, ensuring proper detection
regardless of the number of keys in the slot.

Check for deadline errors (is_under_min_distance_next, is_under_min_distance_previous, out_of_sync) on ALL deadlines before filtering.
Previously, if a deadline with errors was filtered out (not visible), the error message 'Projekti ei ole ajan tasalla' would not display.