feat: add guarded Taskmarket action provider

[iiZeRo]

Description

Adds a TypeScript Taskmarket action provider that lets AgentKit users:

• browse open Taskmarket tasks with mode, tag, reward, and deadline filters;
• inspect current task state and permitted actions;
• calculate competition-adjusted expected value before committing work;
• submit prepared artifacts through a host-provided callback only after explicit user confirmation.

The provider is read-only by default. It never receives or stores a private key, cannot create or fund tasks, and only delegates a submission when the host opts in, the exact confirmation phrase is present, and Taskmarket reports a free worker submission action.

Tests

Added six focused unit tests covering:

• task filter serialization and USDC base-unit conversion;
• competition-adjusted economics;
• submissions disabled by default;
• exact confirmation enforcement;
• live free-submission eligibility revalidation;
• structured API errors.

Local git diff --check passes. The full Jest run could not be completed locally because npm registry downloads repeatedly timed out while installing the monorepo's locked dependency graph; CI should provide the authoritative run.

Checklist

• Added documentation to all relevant README.md files
• Added a changelog entry

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1