[feat] Add external CAPTCHA solver stage with 2Captcha support

[IkariDevGIT]

Problem

Some CAPTCHAs still fail with the built-in solvers.

Proposed solution

Add an optional CAPTCHA solver stage, starting with 2Captcha.

Try local solving first. If it fails, optionally use 2Captcha and continue the same browser session.

Alternatives considered

Local-only solving is free, but not reliable for every CAPTCHA.

A separate external wrapper would duplicate TRAWL's session and browser handling.

Tier impact

TRAWL has a 4-tier escalation ladder (HTTP → cached session → fresh CF solve → residential proxy). Does your feature:

• Fit inside an existing tier?
• Require a new tier or solver?
• Apply cross-cutting (caching, observability, config)?

Add it as a new external CAPTCHA solver stage under:

packages/tiers/src/tiers/
with provider implementations under:
packages/tiers/src/solvers/

Willingness to contribute

• I'd like to implement this myself and open a PR
• I'd be happy with a maintainer implementing it
• Just a discussion for now

Additional context

Initial support could cover 2captcha, with all its supported captchas.

Other providers could be added later.

[gsmachado]

@IkariDevGIT will you implement this? 😅

[IkariDevGIT]

@gsmachado I am pretty busy right now with multiple projects, I could take a crack at it, but I reckon it would take some time.