Recognize active putting-up-PR claims

[laclance]

Summary

Fix a production competition-detection gap exposed after the historical-PR attribution fix.

In grpc/grpc-go#9470, a contributor wrote before private run #13:

Putting up a PR: route all setters through an update() helper ...

That is explicit active implementation ownership, but the strategic claim parser recognizes nearby forms such as “I'll open a PR” and “I'm implementing” while missing “Putting up a PR”.

This change adds that narrow active-claim phrase family.

Safety boundary

• active forms like Putting up a PR: or Putting up a PR to ... count
• passive/hypothetical wording like Putting up a PR would help ... does not count
• no change to claim age, ownership precedence, linked PR handling, readiness, scoring, or paid verification

Regression coverage

• production-shaped Putting up a PR: ... is recognized
• passive hypothetical wording remains a non-claim

Scope

Only:

• opportunity_scout/strategic/claims.py
• tests/strategic/test_claims.py

This intentionally does not touch draft PR #154's shared-tracker competition logic.