Load heatmap data asynchronously

[silverwind]

Fixes: #21045

• Move heatmap data loading from synchronous server-side rendering to async client-side fetch via dedicated JSON endpoints
• Dashboard and user profile pages no longer block on the expensive heatmap DB query during HTML generation
• Use compact [[timestamp,count]] JSON format instead of [{"timestamp":N,"contributions":N}] to reduce payload size
• Public API (/api/v1/users/{username}/heatmap) remains unchanged
• Heatmap rendering is unchanged, still shows a spinner as before, which will now spin a litte bit longer.

Benchmark (1M action rows, SQLite)

Scenario	Time
Old sync page render	536ms
New async page render	66ms
Heatmap endpoint	464ms (loaded after page is visible)

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This pull request refactors heatmap data loading from synchronous server-side rendering to asynchronous client-side fetching. The change significantly improves page load performance by moving an expensive database query off the critical rendering path. The heatmap data is now fetched via dedicated JSON endpoints after the page becomes visible to the user.

Changes:

• Introduced three new JSON endpoints for async heatmap data loading: /user/heatmap (personal dashboard), /{org}/dashboard/heatmap (org dashboard), and /{username}/-/heatmap (user profile)
• Converted heatmap data format from verbose JSON objects [{"timestamp":N,"contributions":N},...] to compact tuple arrays [[timestamp,count],...] to reduce payload size
• Modified frontend to fetch and render heatmap asynchronously with proper error handling

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
web_src/js/features/heatmap.ts	Made initHeatmap async, added data fetching via GET request, and converts compact array format to heatmap display format
templates/user/heatmap.tmpl	Replaced inline heatmap data with data-heatmap-url attribute and updated locale string to use placeholder
routers/web/web.go	Registered three new JSON endpoints for personal, org, and profile heatmap data
routers/web/user/profile.go	Added Heatmap handler for user profile, returns compact JSON format with permission checks
routers/web/user/home.go	Modified Dashboard to set heatmap URL instead of data, added DashboardHeatmap handler for async data fetching
models/activities/user_heatmap.go	Added heatmapDataJSON helper and two new JSON-returning functions for compact data format

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[silverwind]

Diff is minimal now, everything is working.

[silverwind]

Comments addressed and one regression from that fixed (org dashboard). Tests for the JSON endpoints incoming.

[wxiaoguang]

The refactoring does:

1. Remove dead code like GetTotalContributionsInHeatmap
2. Split prepareHeatmapURL code into its function, to avoid bloating func Dashboard
3. Don't call getDashboardContextUser in the heatmap endpoint. getDashboardContextUser does too much.
4. To avoid misuse of getDashboardContextUser, rename it to prepareDashboardContextUserOrgTeams
5. Remove unnecessary ActivityReadable check in user.Heatmap, GetUserHeatmapDataByUser already does so
6. Share same logic in DashboardHeatmap, remove duplicate user.Heatmap
7. Make heatmap entpoints use same route pattern like /issues and /issues/{team}
8. Fix test name t.Run("UserDashboard" to t.Run("OrgDashboard"
9. Rename GetUserHeatmapDataByUserTeam to GetUserHeatmapDataByOrgTeam and make it explicitly accept "org" argument

[wxiaoguang]

The refactoring does:

When AI reaches this level, I can delegate my work to it.

[silverwind]

Thanks for cleaning up

[silverwind]

I tested all heatmaps, all working.