Update incidents icon animation to draw exclamation sequentially

Replaced the shake animation on the incidents icon with a draw animation that sequentially draws the exclamation line from top to bottom (0-60% of animation), then shows the dot (60-100%). Animation completes in 0.3s.

What was the motivation & context behind this PR?

User requested in Slack to change the incidents icon animation from shaking on hover to drawing the exclamation mark sequentially. The SVG was also updated to a new design provided by the user. After initial implementation, the user requested speed adjustments (0.8s → 0.5s → 0.3s).

Slack thread: https://buildwithfern.slack.com/archives/C09NRQ471UK/p1761941230058009?thread_ts=1761941230.058009

How has this PR been tested?

⚠️ NOT VISUALLY TESTED - The animation was not tested by hovering over the actual incidents icon because it requires authentication to access the dashboard navigation. All changes were made based on code analysis and mathematical calculations. CI passes but manual visual verification is critically needed.

Review checklist - IMPORTANT

Must verify visually:

1. Animation appearance: Hover over the incidents icon in the dashboard navigation and verify the line draws smoothly from top to bottom, followed by the dot appearing
2. Stroke-dasharray accuracy ⚠️: The hardcoded value of 3.125 was calculated mathematically from the path coordinates but may not match the actual rendered path length. Watch for:
   • Gaps or jumps in the line drawing
   • Line not fully drawing to completion
   • Line appearing all at once instead of drawing
3. Timing: The 60% split (line completes at 60%, dot shows after) was chosen without visual testing and may need adjustment
4. Duration: The 0.3s duration went through multiple untested iterations (0.8s → 0.5s → 0.3s). Verify it doesn't feel too rushed or too slow
5. No visual regressions: Verify the icon looks identical when not animating (splitting into 3 paths could cause subtle rendering differences)
6. Dark mode: Test in both light and dark themes
7. Accessibility: Verify prefers-reduced-motion properly disables the animation

Technical changes:

• Updated AlertIconAnimated component to use new SVG structure with separate paths for triangle, exclamation line, and dot
• Added alert-draw-line keyframe animation using stroke-dasharray/stroke-dashoffset
• Added alert-show-dot keyframe animation using opacity
• Updated CSS selectors from .alert to .alert-line and .alert-dot

Link to Devin run: https://app.devin.ai/sessions/59f25a7775e048cbad54c2a0d05cbba7
Requested by: Kapil Gowru ([email protected]) (@kgowru)