Installer now creates/updates CLAUDE.md with CodeGraph instructions

- Added claude-md-template.ts with the instructions template
- Installer writes to ~/.claude/CLAUDE.md (global) or ./.claude/CLAUDE.md (local)
- Smart detection: updates existing CodeGraph section or appends if not found
- Uses HTML comment markers for reliable section replacement on upgrades

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/installer/claude-md-template.ts

@@ -0,0 +1,44 @@
+/**
+ * CLAUDE.md template for CodeGraph instructions
+ *
+ * This template is injected into ~/.claude/CLAUDE.md (global) or ./.claude/CLAUDE.md (local)
+ * Keep this in sync with the README.md "Recommended: Add Global Instructions" section
+ */
+
+// Markers to identify CodeGraph section for updates
+export const CODEGRAPH_SECTION_START = '<!-- CODEGRAPH_START -->';
+export const CODEGRAPH_SECTION_END = '<!-- CODEGRAPH_END -->';
+
+export const CLAUDE_MD_TEMPLATE = `${CODEGRAPH_SECTION_START}
+## CodeGraph
+
+CodeGraph builds a semantic knowledge graph of codebases for faster, smarter code exploration.
+
+### If \`.codegraph/\` exists in the project
+
+**Use codegraph tools for faster exploration.** These tools provide instant lookups via the code graph instead of scanning files:
+
+| Tool | Use For |
+|------|---------|
+| \`codegraph_search\` | Find symbols by name (functions, classes, types) |
+| \`codegraph_context\` | Get relevant code context for a task |
+| \`codegraph_callers\` | Find what calls a function |
+| \`codegraph_callees\` | Find what a function calls |
+| \`codegraph_impact\` | See what's affected by changing a symbol |
+| \`codegraph_node\` | Get details + source code for a symbol |
+
+**When spawning Explore agents in a codegraph-enabled project:**
+
+Tell the Explore agent to use codegraph tools for faster exploration.
+
+**For quick lookups in the main session:**
+- Use \`codegraph_search\` instead of grep for finding symbols
+- Use \`codegraph_callers\`/\`codegraph_callees\` to trace code flow
+- Use \`codegraph_impact\` before making changes to see what's affected
+
+### If \`.codegraph/\` does NOT exist
+
+At the start of a session, ask the user if they'd like to initialize CodeGraph:
+
+"I notice this project doesn't have CodeGraph initialized. Would you like me to run \`codegraph init -i\` to build a code knowledge graph?"
+${CODEGRAPH_SECTION_END}`;