v0.14.1 — Configure Models UX polish

Install: Download moa-bridge-0.14.1.vsix below, then code --install-extension moa-bridge-0.14.1.vsix.

What's new since v0.13.0

Single-select now actually shows checkmarks. VSCode's showQuickPick({ canPickMany: false }) silently ignores the picked field — checkmarks only render with canPickMany: true. Introduced singlePickWithCheckbox<T>() built on createQuickPick + canSelectMany: true with real-time onDidChangeSelection validation:
- 0 selected → circle-slash icon
- 1 selected → check icon (confirm enabled)
- ≥2 selected → warning icon, confirm disabled with inline message
- Three submit paths wired: Enter key, ✓ button click, onDidAccept.
Configuration now persists to both User + Workspace tiers by default. saveConfiguration() signature changed from Promise<ConfigurationTarget | null> to Promise<boolean>; iterates [Global, Workspace] targets writing refs/aggregator/reconModel/l3Summarizer to both. Eliminates the previous awkward "which tier?" prompt and the silent precedence issue (User tier cannot override Workspace tier).

moa.reconModel config ({ provider, model } or empty): when non-empty, the recon phase uses this model instead of the aggregator. Empty value falls back to aggregator — preserves v0.13.x behavior.
moa.l3Summarizer config ({ provider, model } or empty): when non-empty, the L3 grandchild agent uses this model. Empty value disables L3 entirely.
Configure Models expanded to 4 steps: refs (multi) → aggregator (single) → reconModel (single, includes "= aggregator fallback") → l3Summarizer (single, includes "= disabled").