chore: allow temporary journeys in pr qa notes

[ovitrif]

Counterpart: synonymdev/bitkit-ios#784

Description

Some bug reproductions need a journey that only makes sense before the fix, or only with a local change that must not be committed: a debug hook, an injected delay, a patched build, or fixture data that will not exist on master. Committing such a journey leaves a dead file in journeys/, and leaving it out of the PR loses a reproduction the reviewer could run.

• Add a temporary keyword to #### Journeys, next to new and updated, for a journey that is carried in the PR body rather than committed.
• The PR body holds a temporary journey in a collapsed <details> block, as fix: keep lnurl pay comment as activity note #1310 did. A setup that needs a code change carries that change as a .diff in the same block.
• State the rule in .agents/commands/pr.md and the PR template: temporary is only for a journey that needs a code change or data that will not exist on master. A bug-fix reproduction that stays valid after the fix is committed as the regression journey.

Raised by jvsena42 in #1250 (comment) and synonymdev/bitkit-ios#743 (comment).

Out of Scope

• Tooling that applies the .diff or runs a temporary journey automatically.