Fix DELETE /v1/note/share to parse ID from JSON request body

[egeozcan]

Fix DELETE /v1/note/share to correctly extract the note ID from a JSON request body instead of only query parameters.

The endpoint used http_utils.GetUIntFormValue which ignores JSON payloads. Added logic to parse the request body and fallback to unmarshaling JSON to retrieve id or noteId.

---

PR created automatically by Jules for task 3263962093540364728 started by @egeozcan

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.

[egeozcan]

Review findings, all fixed in the pushed commit:

• float64 to uint conversion truncated 1.5 to 1 and wrapped negative or huge values onto other notes. Now json.Number through parseUintStrict; non-whole or non-positive IDs answer 400.
• The body was read unbounded and regardless of Content-Type. Now only for application/json, capped at 4 KiB.
• Imports were not gofmt-ordered.
• No tests: added api_tests for noteId, id, invalid values (note must stay shared) and query-string precedence.
• Docs: docs-site/docs/api/notes.md now describes the JSON body.
  Compatibility: query string and form IDs behave as before and still take precedence. The mr CLI uses the query string and is unchanged. POST /v1/note/share still does not read a JSON body (out of scope here). OpenAPI RouteInfo has no request-body field for this route, so the spec is unchanged.

[google-labs-jules]

Review findings, all fixed in the pushed commit:

• float64 to uint conversion truncated 1.5 to 1 and wrapped negative or huge values onto other notes. Now json.Number through parseUintStrict; non-whole or non-positive IDs answer 400.
• The body was read unbounded and regardless of Content-Type. Now only for application/json, capped at 4 KiB.
• Imports were not gofmt-ordered.
• No tests: added api_tests for noteId, id, invalid values (note must stay shared) and query-string precedence.
• Docs: docs-site/docs/api/notes.md now describes the JSON body.
  Compatibility: query string and form IDs behave as before and still take precedence. The mr CLI uses the query string and is unchanged. POST /v1/note/share still does not read a JSON body (out of scope here). OpenAPI RouteInfo has no request-body field for this route, so the spec is unchanged.

Acknowledged. I've fetched the changes pushed by the user and confirmed the tests are passing.