Storage ports: ChatStore/GraphStore/JobStore + adapters + core inversion (stage 3)

Per-entity semantic ports (src/core/ports.ts), one adapter family
(src/store/*, fs JSON/JSONL), exactly one composition point
(src/server/stores.ts). Dependency direction is now machine-checked:
adapters implement core interfaces; core never imports an adapter.

The inversion:
- core/graph.ts (emitChat/getGraph/graphSnapshot/foldStaleChats) is now
  pure — it takes the storage ports as explicit parameters (GraphDeps).
  No store imports; newGraphNodeId is local; node id format unchanged.
- core/graph-context.ts buildGraphContext() no longer defaults to the
  live ledgers: the chat-handler hands in getGraph(graphStore) per turn.
- store adapters export exactly one object each implementing their port
  (chatStore/graphStore/jobStore); bodies otherwise verbatim.
  NodeMapping + SessionCheckpoint moved store/graph -> core/contracts
  (they ARE contract shapes); CreateJobInit/JobPatch live in ports.
- titleFromPrompt moved store/chats -> core/contracts (pure helper,
  planNodeStatus precedent). Store modules now contain persistence only.
- server/stores.ts is the composition root; server/{chats,graph,jobs}.ts
  and chat-handler wire from it; agent (plan tools, sub-agent runner)
  call the port objects. The shell surface (@/src/server exports) is
  unchanged.

Lint law extended: the whole of src/core is now a purity zone (was a
file glob with a graph/graph-context exemption). Verified it fires on
core->store imports; tsc clean, 190/190 tests, eslint clean, prod build
clean (prerender 6/6). Tests pass deps explicitly — graph.test uses the
same fs-adapter pair stores.ts wires in production; graph-context.test
keeps its in-memory ledgers as a GraphStore implementation.

README.md

@@ -71,7 +71,7 @@ graph TB
         VIS["visual-maker<br/>write → render → look"]
     end
 
-    subgraph STORE["File stores (data/, never in git)"]
+    subgraph STORE["File stores (src/store adapters → data/, never in git)"]
         CHATS[("data/chats/*.json<br/>UIMessages + plan tree")]
         JOBS[("data/jobs/*.json")]
         LEDG[("data/graph/*.jsonl<br/>nodes/edges/events/mappings/sessions")]
@@ -126,10 +126,15 @@ src/
     subagents/                  researcher · demo-builder · visual-maker,
                                 runner (async protocol), headless Chrome helper
   server/chat-handler.ts       one chat turn: stream, persist, spawn, emit
+  server/stores.ts              THE composition root — the one place adapters wire in
   core/contracts.ts             THE contracts file — types + protocol docs
+  core/ports.ts                 storage ports — ChatStore · GraphStore · JobStore
+                                (core code depends on these types only)
   core/                         question-core, plan-tree, phases, pending,
                                 graph (emission/derivation), graph-context, math delims
-  store/                        chats · graph ledgers · jobs (plain fs, no framework)
+                                — all pure: storage arrives as parameters
+  store/                        fs adapters implementing the ports: chats ·
+                                graph ledgers · jobs (plain fs, no framework)
 scripts/bench-graph.ts          sigma/forceAtlas2 layout benchmark
 data/                           chats/ · graph/ · jobs/ — runtime state, git-ignored
 ```