fix(grok-local): restore turn boundaries in streaming reasoning text (#6142)

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies
> - The `grok-local` adapter streams reasoning text to the issue
"Working..." panel as the grok CLI runs
> - The `grok` CLI's `--output-format streaming-json` mode silently
drops the `\n` separator between reasoning turns around tool calls
> - Consecutive `thought` chunks (e.g. `` "`" `` followed by `"The"`)
arrive with no intervening whitespace event, so the UI's `delta: true`
concatenator merged them into run-on text like `"…planningGreat, now I
have the issue descriptionThe only co"`
> - This PR adds a small turn-boundary helper that detects sentence
boundaries in the upstream `thought` stream and inserts a single `\n`
only when the previous chunk ended with sentence punctuation (or a
balanced closing backtick) AND the next chunk begins a new uppercase
sentence
> - The benefit is readable streaming reasoning in the UI without
changing how completed messages are stored

## What Changed

- Added `packages/adapters/grok-local/src/shared/turn-boundary.ts` with
per-stream state (last chunk + backtick parity) and a
`restoreTurnBoundary()` helper that inserts `\n` only between balanced,
sentence-terminated `thought` chunks
- Wired the helper into `parseGrokJsonl` (server) and added a new
`createGrokStdoutParser` factory used by `grokLocalUIAdapter` for the
live "Working..." panel
- Added focused tests in `shared/turn-boundary.test.ts`, plus regression
assertions in `server/parse.test.ts` and `ui/parse-stdout.test.ts`

## Verification

- `pnpm --filter @paperclip/grok-local test` — 23/23 adapter tests pass
- `pnpm --filter @paperclip/grok-local typecheck` and UI typecheck —
clean
- Replayed an actual broken `grok 0.1.210` stream from the report;
previously-merged boundaries (`` `ls`The ``, `returned:Confirmed`) now
render with a separating newline; chunks inside un-closed backtick spans
are left alone

## Risks

- Low risk. Boundary insertion only fires when prev ends with
`.`/`!`/`?`/balanced `` ` `` and next begins with an uppercase ≥2-char
word, with no whitespace on either side. Worst case: a rare missed split
or a misplaced newline inside reasoning — both purely cosmetic and
confined to the live streaming panel.

## Model Used

- Claude Opus 4.7 (claude-opus-4-7), Anthropic, extended thinking + tool
use via Claude Code

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [ ] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

packages/adapters/grok-local/src/server/parse.ts

@@ -1,4 +1,5 @@
 import { asString, parseJson, parseObject } from "@paperclipai/adapter-utils/server-utils";
+import { applyTurnBoundary, createTurnBoundaryState } from "../shared/turn-boundary.js";
 
 export interface ParsedGrokJsonl {
   sessionId: string | null;
@@ -32,6 +33,7 @@ export function parseGrokJsonl(stdout: string): ParsedGrokJsonl {
   let errorMessage: string | null = null;
   const thoughtParts: string[] = [];
   const textParts: string[] = [];
+  const thoughtBoundary = createTurnBoundaryState();
 
   for (const rawLine of stdout.split(/\r?\n/)) {
     const line = rawLine.trim();
@@ -43,7 +45,7 @@ export function parseGrokJsonl(stdout: string): ParsedGrokJsonl {
     const type = asString(event.type, "").trim();
     if (type === "thought") {
       const text = asString(event.data, "");
-      if (text) thoughtParts.push(text);
+      if (text) thoughtParts.push(applyTurnBoundary(thoughtBoundary, text));
       continue;
     }