fix(web): reject drafts whose digits or types would not survive being sent

Copilot's seventh pass, three comments, all the same class: the editor showing
one value while the wire carries another.

- `JSON.parse` rounds a whole number past 2^53−1 to the nearest double, so a
  draft reading `{"id":9007199254740993}` submits `…992`. New
  `hasRoundedInteger`, applied by all four JSON-draft parsers — the raw
  arguments editor, `SchemaJsonField`, the Edit-and-replay modal, and
  `parseJsonObjectDraft`, which Copilot did not flag but shares the defect.

  It is narrower than "unsafe integer": it also requires the number's shortest
  form to be written out in full, because JS stringifies from 1e21 upward in
  exponent form and such a value was typed that way — `{"n":1e308}` is a
  legitimate `_meta` value that `parseJsonObjectDraft`'s tests already pin as
  accepted. It still refuses the rare full-form integer that happens to be
  exactly representable, erring toward refusing a sendable value rather than
  misreporting an unsendable one — the trade `toNumericValue` already makes.

- `getPrompt` runs `convertPromptArguments`, which JSON-stringifies every
  non-string argument, so `{"count":2}` leaves as `{"count":"2"}` while the
  editor still shows a number. `reshapedReplayParam` now rejects a non-string
  prompt argument. Not a workaround: the spec types
  `GetPromptRequest.params.arguments` as `Record<string, string>`, so a string
  is the only thing a prompt argument can be. `tools/call` is untouched —
  `callTool` sends its arguments as given.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UL9retfvAXRgvi6EWk4SY4
Signed-off-by: cliffhall <cliff@futurescale.com>

clients/web/src/components/groups/EditReplayModal/EditReplayModal.test.tsx

@@ -197,6 +197,26 @@ describe("EditReplayModal", () => {
     ).toBeInTheDocument();
   });
 
+  // `JSON.parse` rounds a whole number past 2^53−1 to the nearest double, so
+  // the draft shows digits the wire will not carry.
+  it("disables Send for a whole number that loses digits when parsed", async () => {
+    renderWithMantine(<EditReplayModal {...baseProps} method="tools/call" />);
+    await setAceText('{"name":"echo","arguments":{"id":9007199254740993}}');
+    expect(screen.getByRole("button", { name: "Send" })).toBeDisabled();
+    expect(
+      screen.getByText(/Whole numbers must be within/),
+    ).toBeInTheDocument();
+  });
+
+  it("disables Send for a non-string prompt argument", async () => {
+    renderWithMantine(<EditReplayModal {...baseProps} method="prompts/get" />);
+    await setAceText('{"name":"greet","arguments":{"count":2}}');
+    expect(screen.getByRole("button", { name: "Send" })).toBeDisabled();
+    expect(
+      screen.getByText(/`count` would be sent as JSON text/),
+    ).toBeInTheDocument();
+  });
+
   it("closes without sending when cancelled", async () => {
     const user = userEvent.setup();
     const onSend = vi.fn();