feat(browser): add reportCaller to surface user callsite

[dev-KingMaster]

Summary

• Adds an opt‑in browser option, browser.reportCaller.
  • Object mode (asObject or formatters): adds caller string (file:line:column) to the log object.
  • Default mode: appends the caller string as the last console argument.

Motivation

• Addresses Pino browser filename and line reporting #687 where devtools show pino internals (browser.js) as the origin; this surfaces the actual callsite for quicker debugging.

Implementation

• Best‑effort via Error stack parsing with filtering of internal frames; browser‑only.
• Docs: Browser API updated with usage and caveats.
• Types: pino.d.ts updated to include reportCaller?: boolean.
• Tests: adds coverage for asObject mode; default mode verified manually and documented (reduced assertion scope to keep tests stable across environments).

Backward compatible

• Off by default; no changes to Node/server path.

[dev-KingMaster]

Hi @jsumners Could you review the pr and leave any comments? Thanks

[mcollina]

lgtm

[dev-KingMaster]

Hi @mcollina Thanks for approval. Does this pr need to wait for another approval to be merged? Or do I have to do sth on my side?