fix: issue-triage quick wins (extraction, MCP probes, gitignore, CJK, impact) (#654)

Batch of small, localized fixes from an open-issue triage:

- .codegraph/.gitignore now ignores everything but itself, so the database,
  daemon.pid, sockets, and logs stop showing up in git status (#492, #484)
- MCP server answers resources/list and prompts/list with empty lists instead
  of -32601, clearing scary log lines in opencode/Codex (#621)
- index SAP HANA .xsjs/.xsjslib as JavaScript (#556) and TS .mts/.cts (#366)
- visit anonymous AMD/CommonJS/IIFE wrapper bodies so their inner functions and
  calls are indexed instead of coming up empty (#528)
- batch the changed-file lookup so a huge first sync no longer hits
  "too many SQL variables" (#540)
- list files with `git ls-files -z` so non-ASCII/CJK paths survive
  core.quotepath and are no longer silently skipped (#541)
- attach Go methods on generic receivers (*T[P]) to their type (#583, RC1)
- impact no longer climbs the structural `contains` edge, so a leaf symbol
  stops dragging in its sibling methods (#536)
- README: explicit `codegraph install` step, run in a new shell (#631)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -13,6 +13,15 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 - The background file watcher no longer exhausts your machine's file-descriptor budget. On macOS it previously kept **one open file handle per watched file**, so on a large project the running MCP server could pile up tens of thousands of handles and blow past the system-wide limit — at which point *unrelated* apps (your shell, editor, Docker, browser) started failing with "too many open files" until the codegraph process was killed. The watcher now uses a single recursive watch on macOS and Windows, and bounded per-directory watches on Linux, so its cost stays flat no matter how large the project is. (#644, #496, #555, #628, #579)
 - Indexing a project with very symbol-dense files (tens of thousands of functions or methods in a single file) no longer runs out of memory. The step that links dynamic call relationships used to load every function and method into memory at once, which could exhaust the heap and abort indexing with "JavaScript heap out of memory" on large or generated codebases; it now streams them, so memory stays flat no matter how many symbols the project has. (#610)
+- Indexing a very large repository no longer aborts during its first sync with a "too many SQL variables" error. (#540)
+- Files under directories with non-ASCII names (for example CJK characters) are no longer silently skipped during indexing. (#541)
+- The `.codegraph/` index folder no longer clutters `git status`: its generated ignore file now excludes everything in the folder except itself, so the database, `daemon.pid`, sockets, and logs stop showing up as untracked changes. (#492, #484)
+- SAP HANA `.xsjs` / `.xsjslib` files are now indexed as JavaScript. (#556)
+- TypeScript `.mts` and `.cts` module files are now indexed instead of being skipped. (#366)
+- JavaScript modules that wrap their code in an anonymous function — AMD/RequireJS, NetSuite SuiteScript, IIFE bundles — now have their inner functions and calls indexed, instead of the file coming up nearly empty. (#528)
+- Go methods declared on generic types (e.g. `func (s *Stack[T]) Push(...)`) are now correctly attached to their type, so callers, callees, and impact include them. (#583)
+- Asking what a symbol impacts no longer drags in every unrelated sibling method of its class — impact now follows real dependencies instead of the structural "contains" relationship, keeping the result focused on what actually depends on the symbol. (#536)
+- CodeGraph's MCP server now answers an agent's `resources/list` and `prompts/list` probes with an empty list instead of an error, clearing the `-32601` messages some clients (opencode, Codex) logged on connect. (#621)
 
 ## [0.9.9] - 2026-06-02