fix(phase-lifecycle): prevent plan-line overwrite when **Plans:** is bare

\s* after **Plans:** matches newlines, causing [^\n]+ to consume the first
plan checkbox when the **Plans:** field has no value on the same line.
Additionally, the lazy [\s\S]*? could cross section boundaries when the
current section had no **Plans:** value, corrupting a later section.

Fix 1: replace \s* with [ \t]* to restrict post-colon match to horizontal
whitespace only.
Fix 2: replace [\s\S]*? with (?:(?!\n#{2,4})[\s\S])*? to prevent the
pattern from crossing into a new section heading.

Closes #2728

sdk/package-lock.json

@@ -22,7 +22,7 @@
         "vitest": "^3.1.1"
       },
       "engines": {
-        "node": ">=20"
+        "node": ">=22.0.0"
       }
     },
     "node_modules/@anthropic-ai/claude-agent-sdk": {

sdk/src/query/phase-lifecycle.ts

@@ -1194,7 +1194,7 @@ export const phaseComplete: QueryHandler = async (args, projectDir, workstream)
 
       // Update plan count in phase section
       const planCountPattern = new RegExp(
-        `(#{2,4}\\s*Phase\\s+${phaseEscaped}[\\s\\S]*?\\*\\*Plans:\\*\\*\\s*)[^\\n]+`,
+        `(#{2,4}\\s*Phase\\s+${phaseEscaped}(?:(?!\\n#{2,4})[\\s\\S])*?\\*\\*Plans:\\*\\*[ \\t]*)[^\\n]+`,
         'i',
       );
       roadmapContent = replaceInCurrentMilestone(