test(storage): the spool changes nothing when it is read (MR-STOR-0145)

[cryptskii]

MR-STOR-0145 (storage §8): a node never marks, hides, expires or removes a spool envelope after it is written, and serves a spool only from a position. It was Partial with no test; this adds the tests, and MR-STOR-0145 is now Met.

The gap

The spool's existing tests show it keeps every envelope, deduplicates nothing and opens nothing. But each one read a spool once, from position 0. A node that marked or removed what a device had read, or served from anywhere but the position asked, passed them all.

Two tests, on the spool's router, on Postgres

• a_spool_reads_the_same_from_any_position_however_often_it_is_read: 67 envelopes, more than one page.
  • They are read whole in two pages, in the order sent, with positions rising.
  • The first page, read again, is unchanged.
  • A read from a middle position is exactly the rest.
  • A read after the last holds nothing.
• a_device_acknowledging_what_it_read_changes_nothing: the acknowledge, status and unpositioned-read requests feat(beta): skeletons for beta conformance (does not compile yet) #976 removed are not served, and the spool reads the same after them.

Mutation controls (each restored)

Mutation	Result
spool_list_from_seq deletes what it returns	both red: the re-read is empty
the retrieve route reads from position 0 whatever it is asked	the first red: the second page repeats the first
the acknowledge route is served again	the second red

Records

• CONFORMANCE: MR-STOR-0145 is Met (§8), with finding §6.46. §7's storage row is now Met 44, Partial 33.
• VERIFICATION_MATRIX: one new row, with the mutation results.

Evidence

• Release, on Postgres: the spool's 8 tests pass, and the node's lib suite passes 38/0.
• cargo fmt --check and clippy --all-targets -D warnings are clean.
• ci/conformance_evidence.py passes.
• Gemini gate: satisfied.

Merge order

• #1074 also edits §7's storage and All rows, so whichever merges second needs its Totals recounted when it is updated.
• Until #1076 merges, this branch's Code map carries main's 64 stale pins.
• If CORE or SOFI takes §6.46 first, this finding is renumbered when the branch is updated.