feat: web UI, Python support, incremental indexing, cycle detection +…

[AudreyYZY]

… import-resolution fixes

Fixes

• tree-sitter-languages is incompatible with tree-sitter >= 0.22 and had no wheels for 3.12/3.13; every parser test failed on a clean install. Swapped for tree-sitter-language-pack.
• Relative imports resolved against the project root instead of the importing file, so most dependency_edges were silently missing. resolve_import_path now takes from_file.
• tsconfig.json is JSONC in practice; json.load rejected it and dropped every path alias. Added a JSONC pre-pass.
• '@scope/pkg' npm packages were treated as internal imports; alias patterns are now matched explicitly, with exact rules beating wildcards.
• TS 'paths' targets with a mid-string star ('./src/*.ts') and coexisting exact + wildcard rules for the same name were mis-parsed.
• Asset imports ('./styles.css') counted as broken internal imports.
• dependency_edges were inserted once per imported name; now deduplicated with a weight column and a UNIQUE index.
• 'export ... from' re-exports produced no dependency edge, leaving holes around barrel files.
• BFS helpers emitted duplicate adjacency entries; Mermaid node ids could collide and labels could break the syntax.
• Tests wrote into the developer's real ~/.codeatlas.

Features

• Python parser (functions, classes, methods, module/class-level assignments, absolute and relative imports, call edges) behind a language-dispatching parser front end.
• Incremental indexing keyed on content hash; deleted files are pruned.
• Import cycle detection (iterative Tarjan SCC) + 'cycles' command.
• Structured architecture report ('explain'), JSON 'export', 'projects'.
• Web UI: 'codeatlas serve' — FastAPI backend plus a single dependency-free HTML frontend with an interactive dependency map, file and symbol browsers.

Housekeeping

• LICENSE, CONTRIBUTING.md, CI across 3 OSes with format + mypy + coverage, versioned SQLite schema, project-name sanitising, README/README_CN/CLAUDE.md rewritten. 35 -> 100 tests, 83% coverage.

Claude-Session: https://claude.ai/code/session_017jzzJmrj7U9n7SbduD615V