#36264 wallet rpc: fix stale argument metadata and help text

• Fix outdated argument names and misleading help examples across several wallet RPCs
• Prevents confusion for developers and RPC users debugging wallet calls

Updates wallet RPC error strings and help examples across listtransactions, listsinceblock, and sendmany. Corrects an outdated parameter name in listtransactions ('Negative from' to 'Negative skip'), clarifies listsinceblock's parameter validation error, and updates sendmany help examples to avoid claiming an ignored minconf argument sets confirmations.

Problem: Stale parameter names in error messages and misleading help examples confuse RPC users and developers trying to debug wallet RPC calls.

P4 · cleanup

• P4 because this is cosmetic polish to RPC error messages and help documentation
• Improves clarity for RPC callers but has no impact on fund safety or wallet state

P4 because this is cosmetic polish to error strings and help text in wallet RPCs. The listtransactions error referenced an obsolete argument name ('from' instead of 'skip'), listsinceblock did not name the failing parameter, and sendmany help examples showed a dummy argument as active. While helpful for RPC clarity, these changes have no impact on wallet fund safety, transaction creation, or wallet state.

Membership: Touches wallet RPC implementations and functional tests in src/wallet/rpc/ and test/functional/

Factors: security/stability 0, bug 1, performance 0, user value 1, leverage 0

• Ready for review
• Small and focused patch directly incorporating previous reviewer feedback

The patch is small, focused, and directly incorporates previous reviewer feedback with tests updated.

Author status: active, promptly addressed reviewer feedback via force push

Resolved concerns:

• l0rinc asked to split unrelated fixes into focused commits with clear rationale.
• maflcko questioned editing dead code / deprecated arguments without a proper deprecation cycle; author dropped those commits.

• Feedback on commit structure addressed by splitting commits (l0rinc)
• Dropped edits to deprecated arguments after concerns raised (maflcko)
• No open objections remain

Positive; author addressed structural feedback from l0rinc and dropped disputed commits flagged by maflcko

Both reviewers' comments were addressed by restructuring and dropping contentious commits, leaving only clean minor improvements with no open objections.

• l0rinc requested separate focused commits
• maflcko pointed out that modifying deprecated argument code without deprecation/removal was counterproductive
• MrHodlX dropped the disputed commits and rebased

Review verdicts (DrahtBot): 0

4 lines under test/bench/ci.

• src/wallet/rpc/spend.cpp +4/-4
• src/wallet/rpc/transactions.cpp +2/-2
• test/functional/wallet_listsinceblock.py +1/-1
• test/functional/wallet_listtransactions.py +1/-1

PR 36264 fixes stale argument names and inaccurate examples in wallet RPCs (listtransactions, listsinceblock, and sendmany). It fixes the 'Negative from' error to reference 'skip', names the failing parameter in listsinceblock, and stops sendmany examples from pretending the dummy minconf argument sets confirmations. The problem affects RPC callers troubleshooting invalid requests, though it has no impact on fund safety or wallet behavior. Review state is positive and ready after the author split the commits and dropped edits to deprecated arguments per review.