Add supported stack sort controls to the Svelte UI

[Copilot]

What changed

• Add descending sort-by controls for Events, First, and Last on the Svelte stack table.
• Map those controls to the existing stack_frequent, stack_new, and stack_recent API modes instead of sending unsupported sort parameters.
• Keep session Duration non-sortable because the API has no global duration sort and client-side sorting would be incorrect across pagination.
• Add focused column-contract and accessible interaction tests.
• Merge the latest origin/main into the branch.

Why

The original implementation exposed generic TanStack sorting, which caused stack requests to return HTTP 400 and attempted to sort session duration by a field the API does not provide. This keeps the feature Svelte-only while using the backend contract that already exists.

Verification

• npm run validate
• Focused Vitest coverage for stack column configuration and stack sort header interaction
• git diff --check

Runtime QA

Local AppHost startup was attempted with workspace-isolated Aspire state, but timed out after 120 seconds at Determining projects to restore. Other running Exceptionless worktrees were left untouched, so browser dogfood was not claimed against a different checkout.

Breaking changes

None.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
1 out of 2 committers have signed the CLA.

✅ niemyjski
❌ Copilot
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: b6d3929e96

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[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
Exceptionless.Core	73%	65%	9499	➖
Exceptionless.AppHost	38%	40%	139	❌
Exceptionless.Insulation	23%	23%	205	❌
Exceptionless.Web	84%	67%	6935	✔
Summary	76% (22529 / 29467)	65% (10347 / 15860)	16778	✔

[niemyjski]

Follow-up reviewer-feedback and thermo-nuclear audit completed against live head 8fa187e3b11e937702df62808185c67f1e7de0e3.

Feedback classification:

• The Codex First-sort finding was valid for reviewed commit b6d3929e96, but is already fixed, outdated, and resolved on the current head. RCA: API mode stack_new calls AddFirstOccurrenceFilter, so it changes stack membership/count instead of only ordering the current rows. The current implementation excludes stack_new from StackSortMode, leaves First as plain non-interactive text, and exposes only stack_frequent (Events) and stack_recent (Last). Focused coverage locks that contract.
• The submitted Codex review contains no other findings. There are no human change-request reviews or open review threads.
• The coverage comment is informational; the CLA comment is an external contribution-policy blocker, not a code finding.

The complete five-file branch-vs-main diff also passed the requested thermo-nuclear structural review: no spaghetti/branch growth, boundary leak, duplicate canonical helper, cast/optionality churn affecting correctness, non-atomic update, unnecessary sequential orchestration, or 1,000-line threshold crossing. The 19-line header component earns its boundary by centralizing and testing the accessible pressed-state interaction; no safe code-judo simplification remains beyond removing the unsupported First mode.

Verification on the live head:

• focused Vitest: 2 files, 6 tests passed
• npm run validate: passed; Svelte check reports 0 errors and 0 warnings, formatting and ESLint clean
• npm run test:unit: 29 files, 327 tests passed
• npm run build: passed
• git diff --check origin/main...HEAD: clean
• executable CI checks version, test-client, docker-build, test-e2e, and test-api: all successful

No follow-up code change was required. The sole remaining blocker is the pending external Copilot contributor CLA.