fix: complete Windows compatibility for path handling in qmd.ts

[faisalkindi]

Summary

Building on PR #137's store.ts fixes (HOME fallback, mkdirSync, sqlite-vec DLL, bin entry), this PR addresses the remaining Windows compatibility issues in qmd.ts to fully resolve #31.

Changes

Path resolution (startsWith checks)

• Replace all startsWith('/') absolute path checks with isAbsolutePath() (already exported from store.ts) which correctly handles Windows drive letters (C:\, D:\) and Git Bash paths (/c/)
• Affected functions: contextAdd, contextRemove, getDocument, listFiles

Path normalization (split operations)

• Add normalizePathSeparators() before all split('/') operations on filesystem paths to handle Windows backslashes
• Affected functions: computeDisplayPath, getDocument, listFiles, collectionAdd, detectCollectionFromPath

Collection path matching

• Normalize both real paths and collection paths in detectCollectionFromPath() so C:\Users\... matches correctly against stored collection paths

Shell command spawning

• Use cmd /c on Windows instead of /usr/bin/env bash -c for custom collection update commands

Combined with PR #137, this resolves all 8 issues from #31:

1. ✅ Bash shebang → bin entry points to .ts (PR fix: Windows compatibility for HOME path, mkdir, and sqlite-vec loading #137)
2. ✅ mkdir -p → mkdirSync (PR fix: Windows compatibility for HOME path, mkdir, and sqlite-vec loading #137)
3. ✅ Path resolution assumes Unix → isAbsolutePath() (this PR)
4. ✅ HOME fallback → USERPROFILE (PR fix: Windows compatibility for HOME path, mkdir, and sqlite-vec loading #137)
5. ✅ Hardcoded / separators → normalizePathSeparators() (this PR)
6. ✅ sqlite-vec loading → Windows DLL fallback (PR fix: Windows compatibility for HOME path, mkdir, and sqlite-vec loading #137)
7. ⬜ Tests with Unix paths (non-blocking, can be addressed separately)
8. ⬜ Nix flake excludes Windows (non-blocking)

Test plan

• All changes are guarded — Unix paths are unaffected
• Uses existing isAbsolutePath() and normalizePathSeparators() from store.ts (merged in Add Windows path utilities with cross-platform test coverage #51)
• Needs testing on Windows (I have a Windows 11 machine to verify)

Fixes #31

[faisalkindi]

Testing Results on Windows 11

Tested on Windows 11 x64 with Bun v1.3.9:

✅ Working

• qmd status — correct Windows path (C:/Users/...)
• qmd collection add . --name test --mask "*.md" — indexes files successfully
• qmd search "query" — returns results with correct paths and scores
• qmd collection remove — works correctly
• qmd collection list — shows collections properly

⚠️ Bun Bug (not our code)

• **/*.md recursive glob causes Bun to crash with panic: invalid enum value
• This is a known Bun issue on Windows (oven-sh/bun#14844, duplicate of #15964)
• Workaround: use non-recursive glob (*.md) and add collections per-directory
• Non-recursive globs work perfectly

Environment

• Windows 11 x64
• Bun v1.3.9
• Combined with PR fix: Windows compatibility for HOME path, mkdir, and sqlite-vec loading #137 changes