feat: Add Morph codebase search integration

[DhruvBhatia0]

Summary

• Adds Morph as an optional codebase search backend, replacing the current approach of dumping the entire project into LLM context
• When a Morph API key is configured, follow-up actions (bug fixes, features, answers) use targeted code search instead of full-project reads, significantly reducing token usage on large codebases
• Gracefully falls back to the existing full-code-read behavior when no API key is set or when the search fails

Changes

File	Change
src/services/morph.py	New Morph API client with multi-turn tool loop (ripgrep, read, list_directory, finish)
src/services/morph_prompt.txt	Search agent system prompt
src/config.py	get_morph_api_key() / set_morph_api_key()
sample.config.toml	MORPH key under [API_KEYS]
src/services/__init__.py	Export Morph
src/filesystem/read_code.py	search_code() method with fallback
src/agents/agent.py	Lazy code loading — determines action type before loading context
ui/src/routes/settings/+page.svelte	MORPH key in settings UI

How it works

1. User sends a follow-up message (bug fix, feature, question)
2. The Action agent classifies the intent
3. For answer/feature/bug actions: ReadCode.search_code(prompt) calls the Morph WarpGrep API
4. WarpGrep searches the codebase in up to 4 turns using ripgrep, file reads, and directory listings
5. Returns the complete relevant files (preserving existing prompt contracts)
6. For run/report actions: falls back to full code read (these need broader context)

Notes

• No new pip dependencies — uses requests (already in requirements.txt) and stdlib (xml.etree.ElementTree, subprocess)
• Requires rg (ripgrep) on the host for search tool execution; returns a clear message if unavailable
• All file paths from the API are validated against the project root to prevent path traversal
• Users bring their own Morph API key (configured via the settings UI)

Test plan

• All Python files pass ast.parse syntax validation
• Config getter/setter follow existing pattern exactly
• _file_tree excludes .git, node_modules, __pycache__, binary files
• _validate_path rejects ../../etc/passwd and absolute paths outside project root
• _run_ripgrep finds matches with rg, returns clear message when unavailable
• _read_file handles full reads, line ranges, single lines, and errors
• _parse_tool_calls handles valid XML, malformed XML (regex fallback), and empty input
• _read_full_files reads valid files and rejects path traversal attempts
• search() returns [] when no API key is set
• Full mock API e2e: ripgrep → finish flow returns correct files
• ReadCode falls back to code_set_to_markdown() on empty results or exceptions
• Agent lazy loading: action determined before code context loaded

🤖 Generated with Claude Code