Count the example verify step in progress

[madebygps]

This makes learner-facing progress match what the CLI already records after verify 0 CTF{example}. The example verification now counts toward the visible total, so learners see 1/19 after the bootstrap step without changing certificate or token completion requirements.

Fixes: #87

What changed

• split verify progress counting from certificate/export completion counting
• show progress out of 19 total checks, including the example verification
• keep export and token behavior tied to the 18 real challenges
• update learner docs and the CTF test script to reflect the new 1/19 and 19/19 progress output

Notes

• This intentionally preserves the existing export threshold and token payload semantics at 18 real challenges.
• The test script now checks that the example step advances progress immediately.

Validation

• python -m compileall verify\src
• targeted verify command checks for 1/19, 19/19, and Current progress: 2/18 export messaging

[madebygps]

I manually and locally tested this change and it works great.