test: cover features since 053a9c0d + repair test tooling

Add ~330 tests across server (Jest), client (Vitest), editor-ext (Vitest)
and packages/mcp (node:test) for the gitmost features added since
053a9c0d: AI chat, AI agent roles, public-share assistant, MCP per-user
auth, HTML embed, page templates/embed, realtime tree, tree
expand/collapse, and the AI-settings UI.

Test-tooling fixes (prerequisite, were silently hiding coverage):
- Repair 3 page-template specs broken by the 11-arg TransclusionService
  constructor; they never compiled, so template access-control / content
  -leak / unsync-strip coverage was fictitious.
- Build @docmost/editor-ext before server tests via a `pretest` hook;
  the stale dist omitted the new HtmlEmbed/PageEmbed exports (TS2305).
- Let jest resolve the .tsx email templates: add `tsx` to
  moduleFileExtensions and widen the ts-jest transform to (t|j)sx?.

Behaviour-preserving "extract pure core" refactors that the tests drive:
- server: resolveShareAssistantRequest + uiMessageTextLength
  (public-share controller), decideBasicGate + mapAuthResultToResponse
  (mcp), buildErrorAssistantRecord (ai-chat), jsonbObject export (roles).
- client: render-raw-html + shouldExecute/canEdit, decide-embed-state,
  page-embed picker utils, tree-socket reducers, open/close branch maps,
  isEndpointConfigured/resolveKeyField; buildTreeWithChildren now treats
  a permission-trimmed orphan as a root instead of crashing.

Deferred (need a test DB or HTTP harness, documented in the specs):
repo-level Postgres integration tests and the public-share XFF E2E.
Pre-existing DI/lib0-ESM suite failures are untouched and out of scope.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/server/package.json

@@ -23,6 +23,7 @@
     "migration:reset": "tsx src/database/migrate.ts down-to NO_MIGRATIONS",
     "migration:codegen": "kysely-codegen --dialect=postgres --camel-case --env-file=../../.env --out-file=./src/database/types/db.d.ts",
     "lint": "eslint \"{src,apps,libs,test}/**/*.ts\" --fix",
+    "pretest": "pnpm --filter @docmost/editor-ext build",
     "test": "jest",
     "test:watch": "jest --watch",
     "test:cov": "jest --coverage",
@@ -162,7 +163,8 @@
     "moduleFileExtensions": [
       "js",
       "json",
-      "ts"
+      "ts",
+      "tsx"
     ],
     "rootDir": "src",
     "testRegex": ".*\\.spec\\.ts$",
@@ -182,7 +184,7 @@
           ]
         }
       ],
-      "^.+\\.(t|j)s$": "ts-jest"
+      "^.+\\.(t|j)sx?$": "ts-jest"
     },
     "transformIgnorePatterns": [
       "/node_modules/(?!(\\.pnpm/)?(nanoid|uuid|image-dimensions|marked|happy-dom)(@|/))"