Add additional organization billing information to the Svelte billing settings

[Copilot]

Organizations can enter a billing name, address, VAT ID, and VAT number in the Svelte billing settings. Values use the existing organization data keys and endpoints; clearing a field removes its key.

What changed

• Debounced autosave keeps overlapping submissions and individual key writes sequential, preserving sibling values and edits made during a save.
• Navigation stays on the billing page while edits are unsaved or saving, starts a pending save immediately, and asks the user to navigate again after saving. Leaving the app with unsaved changes uses the browser confirmation.
• Billing mutations reuse the organization cache helper and cancel competing detail/list reads so delayed responses cannot restore older values.
• Invoice history retains amounts, payment status, and invoice actions in a component with populated, empty, loading, and error stories.

Verification

• Frontend unit suite: 786 tests passed across 97 files, including overlapping edits, failed-save retry, and stale list responses.
• npm run validate: passed; Svelte check reported 0 errors and 0 warnings.
• Production and Storybook builds: passed.
• Local Chromium checks at 1440px and 390px cover saving all four fields, reload, cleared-key deletion, failure recovery, and navigation before/during saves. API responses were mocked; this is frontend runtime evidence, not full-stack persistence proof.

Breaking changes

None. Existing API routes, response types, and authorization are unchanged.

[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.
2 out of 3 committers have signed the CLA.

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

[niemyjski]

Follow-up reviewer-feedback and thermo-nuclear audit completed against live head e93c6879c3d0309d7024b4d8d510e42eaa654eb3 and origin/main dc940dd15c8d222d9764080622fdf4583d4546b8.

Feedback inventory and classification:

• GraphQL review threads: 0 total / 0 unresolved.
• Inline review comments: 0.
• Submitted reviews: 0.
• Top-level comments: the coverage report is informational and green; the CLA Assistant notice is an external gate because the Copilot committer cannot sign the CLA. There is no human, Codex, or Copilot code-review finding outstanding at the current live head.

Thermo-nuclear findings:

• No remaining structural blocker or justified code change was found in the complete branch-vs-main diff.
• The invoice table is isolated in an 89-line presentational component with populated/empty/loading/error Storybook states; the billing route is 301 lines and no changed file crosses 1,000 lines.
• Serialized autosaves prevent older responses from overwriting newer input.
• Per-key writes intentionally remain sequential: the backend handlers load and save the whole organization document per request, so parallel sibling-key writes can lose updates. This is correctness orchestration, not incidental serialization.
• Missing/malformed legacy data normalizes safely, cleared values delete their stable keys, generic API access remains organization-scoped, and no API contract changed.
• The PR description’s stale test filenames and unsupported backend-test claim were corrected.

Verification:

• Focused Vitest: 3 files / 11 tests passed.
• npm run check: 0 errors / 0 warnings.
• npm run build: passed.
• npm run build-storybook: passed.
• git diff --check origin/main...HEAD: passed.
• Build workflow 30205531546: API, client, E2E, Docker, and version passed.
• Website workflow 30205531465: passed.

No commit was needed for this follow-up audit. The PR is code-ready and GitHub reports it mergeable; the remaining gates are the existing draft state and pending Copilot CLA.

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
Exceptionless.Insulation	37%	35%	286	❌
Exceptionless.Web	85%	70%	8108	✔
Exceptionless.Core	76%	68%	10538	✔
Exceptionless.AppHost	38%	41%	147	❌
Summary	79% (26384 / 33396)	68% (12267 / 18049)	19079	✔