fw: add all satisfied PIT entry nonces to dead nonce list on multi-match Data

[Harsh23Kashyap]

Fixes #209.

Summary

When a Data packet satisfies more than one PIT entry (e.g. a CanBePrefix Interest for /a and an exact-match Interest for /a/b), the satisfy loop in processIncomingData inserted the out-record nonces of pitEntries[0] into the dead nonce list once per entry, and never recorded the nonces of the remaining entries. A looped Interest carrying one of those unrecorded nonces is then not detected and gets forwarded again until its PIT entry expires.

The fix uses the loop variable pitEntry, matching the single-match branch directly above.

Repro evidence

Go 1.26.6, linux/amd64, ndnd main @ d51682b.

Regression test against unpatched main:

$ go test ./fw/fw/ -run TestDataMultiPitMatchDeadNonceList -v
=== RUN   TestDataMultiPitMatchDeadNonceList
    thread_test.go:88:
        	Error:      	Should be true
        	Messages:   	nonce of /a entry missing from DNL
--- FAIL: TestDataMultiPitMatchDeadNonceList (0.00s)
FAIL
FAIL	github.com/named-data/ndnd/fw/fw	0.004s

Same test against this branch:

$ go test ./fw/fw/ -run TestDataMultiPitMatchDeadNonceList -v
=== RUN   TestDataMultiPitMatchDeadNonceList
--- PASS: TestDataMultiPitMatchDeadNonceList (0.00s)
PASS
ok  	github.com/named-data/ndnd/fw/fw	0.003s

Testing

• New regression test TestDataMultiPitMatchDeadNonceList: two pending Interests (/a CanBePrefix nonce 1111, /a/b exact nonce 2222) with out-records upstream; Data /a/b satisfies both; asserts both nonces land in the dead nonce list. Fails before the fix, passes after.
• go test ./... - all 22 packages pass.
• go vet ./fw/... and gofmt clean.