feat(mcp): qsv installer refactor (#3609)

* refactor(mcp): replace package manager install with GitHub Releases direct download

The qsv_setup installer previously tried Homebrew/Scoop which fails in
GUI environments (Claude Desktop) due to PATH issues. Now downloads the
qsvmcp binary directly from GitHub Releases API, extracts it, and
installs to a discoverable location (/usr/local/bin or ~/.local/bin on
Unix, %LOCALAPPDATA%\Programs\qsv on Windows).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(mcp): complete platform support matrix and harden installer

- Add missing ASSET_SUFFIXES for linux-x64, linux-arm64, and darwin-x64
  so direct download works on Linux and Intel Mac (not just macOS ARM)
- Replace write-then-delete writability check with fs.accessSync(W_OK)
  to avoid leaving stale temp files on crash
- Fix Unix zip extraction to handle nested directory structures by
  extracting full archive then searching for binary (matching Windows behavior)
- Use test.skip with reason messages instead of silent platform guards
  so CI reports clearly show skipped vs passed tests

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(mcp): harden find fallback and add unsupported platform test

Guard against empty-string result from /usr/bin/find when no binary is
found in the extracted zip, and add a test verifying that unsupported
platform keys (freebsd, sunos, aix) return null from the asset suffix
lookup.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(mcp): test against real ASSET_SUFFIXES map and remove redundant guard

Export ASSET_SUFFIXES from installer.ts so the unsupported-platform test
validates the actual map instead of a duplicated local copy. Also remove
the redundant `&& findResult.length > 0` check since an empty string
after .trim() is already falsy.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* chore(mcp): remove qsv installation for platforms that Claude Desktop does not support

* fix(mcp): use auto-detected qsv binary path instead of hardcoded "qsv" default

SkillExecutor and FilesystemResourceProvider both hardcoded "qsv" as the
default binary name, causing ENOENT failures when only qsvmcp is installed.
Now both fall back to config.qsvBinPath which auto-detects qsvmcp or qsv.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(mcp): update qsvBinPath JSDoc to reflect auto-detection default

The FilesystemConfig.qsvBinPath comment still said "default: 'qsv'" after
the previous commit switched to auto-detected paths via appConfig.

Also verified the two review findings:
- maxFilesPerListing: FilesystemConfig never declared this field, so the
  rename to appConfig.maxFilesPerListing is correct (no regression).
- qsvBinPath fallback chain: config.qsvBinPath || appConfig.qsvBinPath is
  necessary since mcp-server.ts passes qsvBinPath in the constructor.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(mcp): align installer tests with removed platform support (e1e9187)

Tests for macOS x64, Linux x64, and Linux ARM64 still expected asset
suffixes after those platforms were removed from ASSET_SUFFIXES. Now
they correctly expect null, fixing the CI failure on ubuntu-latest.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(mcp): address Copilot review — harden installer fetch, escaping, and paths

- Add User-Agent header and AbortSignal timeout to GitHub API and download
  fetch calls, matching the pattern in update-checker.ts
- Escape single quotes in PowerShell string interpolation to prevent
  injection from paths containing apostrophes (e.g. O'Connor)
- Use os.homedir() instead of env var fallbacks (USERPROFILE/"", HOME/"/tmp")
  for reliable install directory resolution
- Fix macOS manual instructions to specify aarch64-apple-darwin asset name
- Fix setup tool hint from "qsv.dathere.com" to "GitHub Releases"

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(mcp): hoist psEscape to module scope and remove redundant escaping of fixed binaryName

Moves psEscape helper from inside the try block to module scope (avoids
unnecessary allocation on non-Windows platforms) and drops the redundant
psEscape(binaryName) call since binaryName is always "qsvmcp"/"qsvmcp.exe".

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: jqnatividad

.claude/skills/src/executor.ts

@@ -168,7 +168,7 @@ export class SkillExecutor {
   private qsvBinary: string;
   private workingDirectory: string;
 
-  constructor(qsvBinary: string = "qsv", workingDirectory?: string) {
+  constructor(qsvBinary: string = config.qsvBinPath, workingDirectory?: string) {
     this.qsvBinary = qsvBinary;
     this.workingDirectory = workingDirectory || process.cwd();
   }