feat: add memory.patch, trim memory.get, unify the memory write path

memory.get no longer returns the embedding and content_tsv
----------------------------------------------------------
It used a bare select() and returned the raw DB row, while memory.list
and memory.search already projected an explicit 9-field shape. On a
~13k-char memory those two internal columns were 55% of the response
and pushed it past the MCP tool-output cap, so large memories could not
be fetched inline at all. memory.get now returns the same 9 fields as
its siblings; user_id is still selected for the authorization check and
stripped before responding.

memory.patch
------------
memory.update only accepts full replacement, so adding one line to a
large document meant resending the whole document — expensive enough
that edits were being skipped rather than risk silently truncating
shared team documents.

memory.patch replaces one exact occurrence of old_string. An absent or
ambiguous match is an error, never a silent no-op and never an
arbitrary pick; that refusal is what makes the operation safe to hand
to an agent. The semantics live in lib/memory-patch.ts as a pure
function, free of DB and auth, so both surfaces share them.

Shared mutation layer
---------------------
The MCP tools and the Web UI Server Actions each reimplemented
authorize -> mutate -> re-embed -> CAS -> audit, and had drifted. Both
now route through lib/memory-mutations.ts.

BEHAVIOUR CHANGE: memory.delete over MCP skipped the project ACL
whenever the caller authored the row, so a memory written while a share
was rw stayed deletable by its author after an owner downgraded that
share to ro. memory.update and the whole Web UI always checked.
Authoring a row now grants no standing write privilege on any path.

The one deliberate difference between the surfaces is injected as a
ProjectResolver: MCP refuses an unknown project key so an agent cannot
spawn near-miss projects off a typo, while the Web UI creates one
because a person typing a name into a form means to.

Tests and lint
--------------
Adds vitest. The integration tests run against a real Postgres rather
than a mocked DB. The embedder sidecar is the only stub and it is
deterministic per-text, so re-embedding is verified by asserting the
stored vector actually changed rather than that a mock was called. One
test pins that content_tsv is a generated column and therefore cannot
rot after a patch — only the embedding needs an explicit recompute.

pnpm lint previously dropped into an interactive `next lint` setup
prompt and exited 1; ESLint had never been configured here. Replaced
with the ESLint CLI and a flat config bridging eslint-config-next
through FlatCompat. Clean at --max-warnings=0.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

apps/web/vitest.setup.ts

@@ -0,0 +1,25 @@
+/**
+ * Test environment. `lib/env.ts` validates a full production config at
+ * import time, so integration tests that touch the DB need these set
+ * before any module under test is loaded.
+ *
+ * Only DATABASE_URL points at anything real — a throwaway Postgres with
+ * pgvector. The OIDC/secret values exist purely to satisfy validation;
+ * tests construct a UserContext directly rather than going through auth.
+ */
+// NODE_ENV is set to "test" by vitest itself.
+//
+// DATABASE_URL points at a throwaway pgvector instance. The default assumes
+// the published port is reachable on localhost; when the test runner is
+// itself inside a container, export DATABASE_URL with the database
+// container's address instead. See README → Running the tests.
+process.env.DATABASE_URL ??= "postgres://test:test@127.0.0.1:55432/shared_memory_test";
+process.env.PUBLIC_URL ??= "http://localhost:3000";
+process.env.OIDC_ISSUER ??= "http://localhost:9000/application/o/test/";
+process.env.OIDC_CLIENT_ID_WEB ??= "test-web";
+process.env.OIDC_CLIENT_SECRET_WEB ??= "test-web-secret";
+process.env.OIDC_CLIENT_ID_MCP ??= "test-mcp";
+process.env.OIDC_AUDIENCE ??= "test-audience";
+process.env.EMBEDDER_URL ??= "http://localhost:8080";
+process.env.NEXTAUTH_SECRET ??= "test-nextauth-secret-at-least-32-chars-long";
+process.env.CLI_TOKEN_SECRET ??= "test-cli-token-secret-at-least-32-chars-long";