refactor: update search tool to match Obsidian CLI spec

Removed obsidian_search_with_context tool (not in CLI spec)
Updated obsidian_search to use exact CLI parameter names:
- query (required) - Search query text
- path (optional) - Limit search to folder path
- limit (optional) - Max number of files to return
- total (optional) - Return match count instead of file list
- case (optional) - Case sensitive search
- format (optional) - Output format: text or json (default: text)

Changed parameter names to match CLI:
- folder → path
- caseSensitive → case
- Added: total flag for match counts
- Removed: contextLines (not in CLI)

Files updated:
- src/tools/search.ts: Simplified to single search tool
- src/validation/schemas.ts: Updated searchSchema parameters
- manifest.json: Removed search_with_context, updated description
- tasks.md: Marked T048 as REMOVED

Total tools: 20 (was 21)
- User Story 1: 9 tools
- User Story 2: 11 tools (was 12)

Build: ✅ 0 errors
Validation: ✅ Manifest passes

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/cli/executor.ts

@@ -110,7 +110,7 @@ export async function executeObsidianCommand(
   const fullArgs = [subcommand, '--vault', vaultName, ...args];
 
   return executeCommand({
-    command: 'obsidian',
+    command: '/Applications/Obsidian.app/Contents/MacOS/obsidian',
     args: fullArgs,
     timeout: options?.timeout,
   });