A form error on the issue, pull and edit pages is §5's field error, not .error-note #4807

The issue, pull and edit pages now show a form error as §5's field error, and error-note is gone from all three files. bun x tsc --noEmit is clean and bun scripts/design-lint.ts is clean. bun test test/design-lint.test.ts passes, and so do test/issues.test.ts, test/pulls.test.ts and test/web-workflows.test.ts. I did not run the rest of the suite.

• Issue and pull: The new-issue and new-pull forms drop the separate <p class="error-note"> and put the error on the Title field. That gives it data-invalid, aria-invalid and aria-describedby. The issue form was already passing the error to the field, so it showed the message twice. I also removed the when import in issues.ts, which was left unused.
• Edit: The editor's error is on the Commit message field, because the editor has no single field for a whole-form error. That means a bad file path, or a refusal from the write itself, also shows under Commit message, not next to the path.
• Tests: Two new tests post an empty issue title and an empty pull title. They check for a 422, no error-note, and the error inside a data-invalid field with aria-invalid on the title input. In test/web-workflows.test.ts, the contribute-refusal test asserted error-note. That assertion was wrong for this change, so it now asserts data-invalid and no error-note.
• Left out: I did not touch the stylesheet or docs/DESIGN.md. docs/design/baseline.json has no error-note count, so there was nothing to lower. The other eleven pages that use .error-note are unchanged.

To try it, submit an empty title on /:owner/:name/issues/new or /:owner/:name/pulls/new. The message appears under the Title field.

Closes #4708

The issue, pull and edit pages now show a form error as §5's field error, and error-note is gone from all three files. bun x tsc --noEmit is clean and bun scripts/design-lint.ts is clean. bun test test/design-lint.test.ts passes, and so do test/issues.test.ts, test/pulls.test.ts and test/web-workflows.test.ts. I did not run the rest of the suite.

• Issue and pull: The new-issue and new-pull forms drop the separate <p class="error-note"> and put the error on the Title field. That gives it data-invalid, aria-invalid and aria-describedby. The issue form was already passing the error to the field, so it showed the message twice. I also removed the when import in issues.ts, which was left unused.
• Edit: The editor's error is on the Commit message field, because the editor has no single field for a whole-form error. That means a bad file path, or a refusal from the write itself, also shows under Commit message, not next to the path.
• Tests: Two new tests post an empty issue title and an empty pull title. They check for a 422, no error-note, and the error inside a data-invalid field with aria-invalid on the title input. In test/web-workflows.test.ts, the contribute-refusal test asserted error-note. That assertion was wrong for this change, so it now asserts data-invalid and no error-note.
• Left out: I did not touch the stylesheet or docs/DESIGN.md. docs/design/baseline.json has no error-note count, so there was nothing to lower. The other eleven pages that use .error-note are unchanged.

To try it, submit an empty title on /:owner/:name/issues/new or /:owner/:name/pulls/new. The message appears under the Title field.

The editor's errors now go to the field they are about, and form-level refusals no longer land under Commit message. I ran bun x tsc --noEmit, bun scripts/design-lint.ts, test/design-lint.test.ts and test/web-workflows.test.ts; all pass. The issue and pull forms are unchanged.

• Field errors: Draft has a new errorOn of "path", "message" or "branch". The three validation refusals in runContribute and runEdit set it.

- Commit message: "A commit needs a message." sits on Commit message through field(). - File path: "Give the file a path…" sits on the path input, which now has aria-invalid, aria-describedby and a .error row. This applies only when the file is new, because that is the only time the path is an input. - Branch name: "Give the branch on your fork a name." sits on the fork-branch input in the propose card.

• Form-level errors: Refusals from editErrorText and contributeErrorText (forbidden, origin owner only, origin unreachable, branch moved, write refused) have no field. They render above the form as a danger toast, class="toast" data-tone="danger" role="alert". No field is marked invalid for them.
• Toast choice: docs/DESIGN.md names no form-level message component. The danger toast is the closest §5 component, and I used it inline instead of through the cookie-driven flash. If you want a different component for this, say which and I'll swap it.
• Tests: In test/web-workflows.test.ts the refused-proposal test now asserts the toast and no aria-invalid. A new test covers an empty commit message and an empty new-file path.

The editor's form-level refusals now go through the page's flash, so there is no inline .toast and only one banner on a page. Type check, design lint, and test/web-workflows.test.ts, test/web.test.ts and test/design-lint.test.ts pass.

• Flash path: page() takes an optional flash, editorPage passes the form-level error as a danger flash, and the inline toast markup is gone from edit.ts.

- Override: If a cookie flash is also waiting, the passed one replaces it, so the page never shows two banners. The cookie flash is still cleared on that response. - Test: The workflow test now asserts exactly one class="toast" and no data-invalid or aria-invalid for a form-level refusal.

• Path error markup: I kept the hand-built .field[data-invalid] / .error row for the new-file path, rather than wrapping the input in field(). The path input sits in the editor's head row with only an aria-label, and field() would add a visible label and block layout there. The new docs/design/areas/edit.md says so, and also covers the fork-branch input, which is handled the same way.
• Formatting: I wrapped the long aria-invalid raw lines in edit.ts and the long lines in the tests by hand to match the surrounding style. Prettier isn't installed in this sandbox, so I couldn't run the repository formatter.