test,chore: clear the static and coverage lanes for the cache stack

Static: the cache package.json files array matches the workspace
constraint shape, the unused dsh-storage-json devDependency is dropped
(tests run on the memory backend), and docs/module-graph.md is
regenerated for the new package edge.

Coverage: two unreachable branches deleted rather than tested —
coldSnapshot's floor-0 tail reuse (a baseSeq-0 restore never throws and
an unrelated record still carries a usable watermark) and flushSoft's
non-mandatory clean-skip (throttle triggers only fire dirty). New tests
close the real gaps: write() on a never-dirty session and the non-JSON
unit-state rejection, plugin disposal clearing armed interval timers,
cachedSnapshot's all-version-mismatched and cwd-identity arms, the
zero-units empty-log cut, the coordinator seek-hook ladder (suffix /
not-found / plain failure / abort-reason relay), and the superseded-
retirement race proving forget()'s exact-entry guard.

packages/session-projection/session-projection-cache/package.json

@@ -21,7 +21,6 @@
   "files": [
     "lib/index.js",
     "lib/invariant.js",
-    "lib/types/**/*.js",
     "lib/types/**/*.d.ts",
     "lib/types/**/*.d.ts.map",
     "src"
@@ -46,7 +45,6 @@
     "@deepseek-ai/dsh-session-projection": "workspace:^",
     "@deepseek-ai/dsh-storage": "workspace:^",
     "@deepseek-ai/dsh-storage-domain": "workspace:^",
-    "@deepseek-ai/dsh-storage-json": "workspace:^",
     "cordis": "^4.0.0-rc.7"
   }
 }