[Bug] apply_patch rejects heredoc wrappers with non-word delimiters

Description

apply_patch accepts shell heredoc wrappers only when the delimiter is \w+. A valid wrapper like cat <<'PATCH-1' is parsed as NotApplyPatch, so the patch never reaches apply_patch.

This is a real user-facing failure because shell heredoc delimiters commonly contain - or other non-word characters.

Expected Behavior

A patch wrapped in a valid heredoc delimiter should be extracted and parsed the same way as <<'EOF'.

Current Behavior

The parser only matches apply_patch\s*<<['\"](\w+)['\"], so PATCH-1 is rejected.

Minimal Repro

import { maybeParseApplyPatch } from "./src/patch/index.ts"

const script = String.raw`apply_patch <<'PATCH-1'
*** Begin Patch
*** Add File: x.txt
+ok
*** End Patch
PATCH-1`

console.log(maybeParseApplyPatch(["bash", "-lc", script]).type)
// NotApplyPatch

Root Cause

The heredoc regex in packages/opencode/src/patch/index.ts only allows \w+ delimiters. The core parser uses the same restriction in packages/core/src/patch.ts.

Suggested Fix

Relax the heredoc delimiter pattern to accept non-whitespace delimiter tokens, and add a regression test for a delimiter like PATCH-1.