fix(lib): detect technologies in informal multi-project directories

[ThurubilliSaiManoj2026]

Fixes #51

Problem

When autoskills is run from a parent folder containing multiple independent
sub-projects (no pnpm-workspace.yaml, no workspaces field, no deno.json
workspace), resolveWorkspaces() returns [] and root detection finds nothing,
resulting in "No technologies detected".

Root Cause

The detection engine in detectTechnologies() only scans sub-directories when
a formal workspace config is present. Plain multi-project folders are not
covered by any existing code path.

Fix

Added scanSubdirProjects() — a private function that scans immediate
subdirectories (1 level deep) for package.json, deno.json, or deno.jsonc
files. This is used as a fallback inside detectTechnologies() when both
conditions are true:

• resolveWorkspaces() returns [] (no formal workspace config)
• Root detection yields zero technologies

Skips SCAN_SKIP_DIRS (node_modules, .git, dist, etc.) and hidden
directories (those starting with .). Does not activate when the root itself
has detectable technologies.

Tests

Added 6 new tests in workspace.test.ts under the describe block
detectTechnologies — informal multi-project directory fallback:

• Detects technologies when root has no package.json
• Detects technologies when root package.json has no deps
• Does NOT trigger fallback when root already has detectable tech
• Skips node_modules during fallback scan
• Skips hidden directories during fallback scan
• Deduplicates technologies across multiple sub-projects