Upgrade to core 0.13 line and adopt the 404/403 anti-oracle rule

[cuibonobo]

Closes #79.

Summary

• Bumps @haverstack/core to ^0.13.1, wire-types to ^0.12.0, adapter-local to ^0.12.0, commons to ^0.5.0, and conformance-fixtures to ^0.6.0 (dev). Confirmed core resolves to 0.13.1 and record-adapter-sqlite to 0.5.1 transitively.
• Adopts the anti-oracle rule: ScopedStack.get() now returns null (rather than throwing) for a record the requester can't read, and the write/history mutators throw StackNotFoundError instead of StackPermissionError in that case — 403 is now earned by readability, not by holding a valid id.
• An anonymous requester now gets 404 + WWW-Authenticate: Bearer for a private record instead of 403 or a bodyless 401 — added centrally in errorMiddleware (fires whenever a StackNotFoundError-mapped 404 reaches an anonymous requester), so it applies uniformly rather than per-route. Bearer (RFC 6750 §3) is the standard WWW-Authenticate scheme for a bearer-token API — this server's actual wire credential — rather than the higher-level did-challenge exchange discovery advertises for obtaining that token.
• Fixed entity.ts's cached owner-record id: it's now only evicted by the owner's own null read. A non-owner's null is ambiguous under the new rule (denied vs. gone) and previously forced a wasted re-resolve query on every forbidden GET /entity. Added a regression test asserting the query isn't re-run.
• requireOwner()-gated routes (tokens, types, entity PATCH, attachment delete/gc) are unaffected — those throw in middleware before any record is read, so they correctly stay 403.
• retainSortDirection's existing validation in queryParsing.ts is unchanged and still the right defense-in-depth alongside core's own hardened ORDER BY check.

Also folded in (shipped in the same dependency range, needed to get the suite green)

Two wire-contract changes were bundled into the same core/wire-types minors and aren't mentioned in #79's checklist, but the suite can't pass without them:

• Mutation responses: soft-delete, associate, dissociate, and setPermissions now answer 200 with the updated record instead of 204 (hard-delete, which produces no record, is unchanged and stays 204).
• Actor stamping: a non-author PATCH now stamps updatedBy/updatedVia on the record. This "arrives for free" — ScopedStack already does it from the session, no route change needed, just a conformance test dispatching the new fixture.

Sweep of toBe(403) assertions (#79's checklist item)

Went through all 29 toBe(403) assertions across tests/. Beyond the two named in the issue (records.test.ts:110,142), found three more read-based cases that also needed to flip to 404, confirmed by actually running the suite against the bumped deps rather than by inspection alone:

• records.test.ts — "an empty permissions array makes the record private" (anonymous GET after PUT /permissions)
• conformance.test.ts — set-permissions-empty-is-private fixture dispatch (same shape)
• entity.test.ts — GET /entity for a non-owner authenticated entity (only requireAuth()-gated, not requireOwner(), so it goes through the same get()-returns-null path)

One test (records.test.ts — soft-DELETE on a _grant record) also flipped, but for a different reason: stack.grant() never gave the grantee read access to the grant record itself, so the test was accidentally exercising the anti-oracle case instead of the write-protection fence it was meant to test. Fixed by granting explicit read+write on the record directly, matching its PATCH sibling test.

Test plan

• pnpm test — 343/343 passing
• pnpm typecheck — clean
• pnpm lint — clean
• pnpm format:check — clean
• New change-feed discovery fixtures (discovery-advertises-a-change-feed, discovery-advertises-a-feed-that-neither-resumes-nor-includes-records) parked in the discovery block's SKIPPED set with a reason pointing at Implement GET /changes (SSE change feed) #82/Advertise the change feed in discovery #83
• No anti-oracle logic added to routes — ScopedStack owns it, per the issue's acceptance criteria

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