feat: implement end-to-end state machine driver (state_machine.py)

[adamsithr]

Bounty Payout Address:

• Network: Solana (SOL)
• Address: 7jXAK7dDBwkAJT67WjPeu8cg577y3x1oMp7ZCSMV18mR

Summary

This PR implements the end-to-end state machine driver in state_machine.py to satisfy Issue #10.

Acceptance Criteria Met

• State Machine Driver (state_machine.py): Implements the driver sequence traversing run states (QUEUED -> CLAIMED -> TRIAGED -> CANDIDATES_RUNNING -> CRITIQUE -> SYNTHESIS -> LOCAL_VERIFICATION -> PR_OPEN) and projects label changes accordingly.
• Process Integration: Integrates and executes coordinator scripts sequentially (claim_issue.py, heavy_coding_flow.py, critique_candidates.py, doctor.py, and publish_pr.py) when --execute is set.
• Mock Inputs: Supports dry-run and mock testing via JSON inputs to run transitions deterministically without external API queries.
• Transition Coverage: Added table-driven tests in tests/test_state_machine_driver.py verifying state transitions.
• CI Validation: Passed Ruff, MyPy, compiling, and pytest coverage (113 passed tests total).

Closes #10