Allow receiver configure session expiry.

[zealsham]

This pr addreses #1515, it allows receiver to set custom expiration time in payjoin-cli.

Pull Request Checklist

Please confirm the following before requesting review:

• I have disclosed my use of
  AI
  in the body of this PR.
• I have read CONTRIBUTING.md and rebased my branch to produce hygienic commits.

[coveralls]

Coverage Report for CI Build 25466196017

Coverage decreased (-0.1%) to 85.045%

Details

• Coverage decreased (-0.1%) from the base build.
• Patch coverage: 21 uncovered changes across 2 files (2 of 23 lines covered, 8.7%).
• No coverage regressions found.

Uncovered Changes

File	Changed	Covered	%
payjoin-cli/src/app/config.rs	13	2	15.38%
payjoin-cli/src/cli/mod.rs	10	0	0.0%

Coverage Regressions

No coverage regressions found.

---

Coverage Stats

Relevant Lines:	13541
Covered Lines:	11516
Line Coverage:	85.05%
Coverage Strength:	399.35 hits per line

---

💛 - Coveralls