feat: expand VS Code extension with 12 new chat commands

[bilersan]

Summary

Fixes #32 — Expands the VS Code chat participant with 12 new command handlers, bringing total coverage from 16 to 28 commands.

New Commands (12)

Command	Handler	Tests
/changes	handleChanges	4
/config	handleConfig	4
/doctor	handleDoctor	2
/guide	handleGuide	4
/why	handleWhy	3
/memory	handleMemory	4
/prompt	handlePrompt	5
/decisions	handleDecisions	3
/learnings	handleLearnings	2
/deps	handleDeps	6
/journal	handleJournal	3
/reindex	handleReindex	3

Other Changes

• splitArgs helper — Parses quoted arguments ("multi word arg") correctly for commands like add task "my task title"
• Activation event — Added onChatParticipant:ctx.participant to ensure the extension activates when users invoke the chat participant
• Windows shell support — execFile calls now use shell: true on Windows for proper PATH resolution
• LICENSE — Added Apache-2.0 license file for the extension package
• Tests — 78 new tests across all new handlers (53 → 131 total, all passing)

Files Changed

File	Change
editors/vscode/src/extension.ts	+683 lines (12 handlers, splitArgs, Windows shell)
editors/vscode/src/extension.test.ts	+830 lines (78 new tests)
editors/vscode/package.json	+52 lines (12 command definitions, activation event)
editors/vscode/README.md	Updated feature list
editors/vscode/LICENSE	New file (Apache-2.0)

Testing

npm run build  ✅ (28.9kb bundle)
npm test       ✅ (131 tests, 535ms)

[bilersan]

Superseded by consolidated VS Code extension PR with full CLI parity (45 commands + Command Palette).