Fix documentation defects found by an adversarial review

Fifteen findings, all verified before acting. The ones that mattered:

- Corrections added without updating what they corrected. §5's table still
  said a cap-less NURI is one "without :k:", two hundred lines after §4
  established the discriminant is `r:`. Same shape of defect in the P1a
  report, which kept the sentence "it is the owner's keyring, upstream the
  keyring is the wallet" — the exact sentence §4quater declares wrong, and the
  one that produced a global in-memory keyring.

- A wrong source citation: RootCapRefresh/BranchCapRefresh live in
  verifier/src/commits/mod.rs, not repo/src/commit.rs, and are no-op stubs.

- Documentation describing deleted code: isolation.ts, discovery.readIndex,
  the global index, and an acceptance test that was dropped with discovery.

- The P1a implementation report had aged into being wrong in four places
  (caps not persisted, inbox processing not started, plain string types, the
  :k: segment). It is dated, so it now carries a header saying what later lots
  overtook, rather than being rewritten.

- vision.md stated "a document's data is stored encrypted" in the present
  tense. That is the target; here the cap value is the constant OK and nothing
  is encrypted. Said plainly now.

- Prose left mangled by an earlier mechanical find-and-replace, in four places
  I had claimed were repaired.

Also: reach.ts and connect.ts had no home in the permanent docs — the boundary
and the connection sequence are now described in simulation.md, not only in a
brief.

docs/nextgraph-current-state.md

@@ -663,7 +663,7 @@ On a FRESH session over the SAME persistent wallet (reconnect, new page, re-logi
 anchored `sparql_query` against a document written in an earlier session comes back with
 **0 rows and no error** — persisted documents read as empty. Observed on every anchored
 reader of the polyfill and healed identically in each (`ensureRepoOpen` before the read,
-`packages/client/src/open-repo.ts`): the discovery index (`discovery.ts` `readIndex`),
+`packages/client/src/open-repo.ts`): the user's own documents,
 the user's store (`store-registry.ts` `readUserStore`), the by-need doc batch
 (`read-model.ts` `readUnion`), and the store-root pointer read (`store-registry.ts`
 `resolvePointer`). The heal is `doc_subscribe(nuri)` → await the first `State` (the sync