feat: add .mjs/.astro extension support and fix IMPORTS_FROM path resolution

[zoneghost7]

Summary

Two changes to parser.py:

1. Extension mappings for .mjs and .astro files

• .mjs → javascript: Standard ES module files (.mjs) are widely used for test suites (*.test.mjs), configs (astro.config.mjs, rollup.config.mjs), and any project preferring explicit ESM. These were silently skipped during parsing. Since .mjs is standard JavaScript with ES module semantics, mapping to javascript is correct.

• .astro → typescript: Astro framework files have TypeScript frontmatter between --- fences followed by an HTML template section. Tree-sitter's TypeScript grammar parses the frontmatter cleanly — extracting imports, function definitions, and call expressions — while silently skipping the template section (no parse errors). This gives useful graph coverage (imports, functions, calls) for Astro projects without requiring a dedicated Astro grammar.

2. Fix IMPORTS_FROM edge path resolution

Problem: IMPORTS_FROM edges store the raw import string as target_qualified (e.g., ../../lib/data-service). However, query patterns like importers_of and find_dependents look up edges by absolute file path. This mismatch causes:

• importers_of returns zero results for every file — the query searches for /abs/path/to/file.ts but the database contains ../../lib/data-service
• find_dependents() in incremental.py fails to identify downstream files during incremental rebuilds — editing a core library file won't trigger re-parsing of its importers
• Blast radius analysis misses all IMPORTS_FROM traversal paths, only finding connections via CALLS edges

Root cause: _resolve_module_to_file() is called when creating CALLS edges (via _resolve_call_target) but is never called for IMPORTS_FROM edges.

Fix: Call _resolve_module_to_file() when creating IMPORTS_FROM edges (lines 601-607). If resolution succeeds, store the absolute path; if it fails (node built-ins like node:fs, external packages like react, virtual modules like astro:content), fall back to the raw string. This is the same graceful-fallback pattern used for CALLS edges.

Before:

importers_of('src/lib/data-service.ts') → 0 results
find_dependents('/abs/path/data-service.ts') → 0 files

After:

importers_of('src/lib/data-service.ts') → WorkLayout.astro, [slug].astro
find_dependents('/abs/path/data-service.ts') → 2 files

Edge cases handled

Import type	Resolution	Stored as
Relative: ../../lib/utils	Resolves via _resolve_module_to_file	Absolute path
Relative with ext: ./Component.astro	Resolves (exact match)	Absolute path
Index barrel: ./utils (dir with index.ts)	Resolves (index file)	Absolute path
Node built-in: node:fs	Returns None → fallback	node:fs (raw)
External package: react	Returns None → fallback	react (raw)
Virtual module: astro:content	Returns None → fallback	astro:content (raw)
Missing file: ./deleted	Returns None → fallback	./deleted (raw)

Test plan

• Full rebuild on a TypeScript/JavaScript project with .mjs test files — verify .mjs files appear in graph stats
• Full rebuild on an Astro project — verify .astro files are parsed, imports and functions extracted, no errors
• importers_of query returns correct results for files with relative imports
• find_dependents correctly identifies downstream files
• Blast radius for a library file includes files connected via IMPORTS_FROM edges
• External/unresolvable imports (node:fs, react, etc.) stored as raw strings (no regression)
• Incremental rebuild after editing a file correctly re-parses its dependents

🤖 Generated with Claude Code

[tirth8205]

Integrated into main via PR #68. Thank you for the contribution! 🎉