feat: smart notifications — built-in throttling, auto app logo detection, and Claude Code readiness

[AdhamHossamm]

Summary

BurntToast notifications just got context-aware. Two features that make toasts smarter about who triggered them and when to stay quiet:

• Notification Throttling (-CooldownSeconds): Built-in spam prevention. A new parameter on both Submit-BTNotification and New-BurntToastNotification that suppresses duplicate toasts within a configurable time window. Each UniqueIdentifier gets its own independent cooldown tracked via lock files in %TEMP%\BurntToast-Throttle. Uses .NET I/O (System.IO.File) instead of PowerShell cmdlets so throttle state persists correctly even under -WhatIf.

• Auto App Logo Detection (-AutoAppLogo + -AppLogoMap): BurntToast now knows who called it. A new switch on New-BurntToastNotification that walks the process tree to find the first ancestor with a visible window (your terminal, IDE, or app shell), extracts its executable icon via System.Drawing, and caches it in %TEMP%\BurntToast-IconCache. The -AppLogoMap hashtable lets you pin custom icons to specific process names — for example, @{ 'node' = 'C:\icons\claude.ico' } gives Claude Code its own branded notifications.

Motivation

Born from real-world Claude Code integration where hook-driven toast notifications had two problems:

1. Rapid subagent completions spammed identical toasts (5-10 in seconds)
2. Every notification used the same generic icon regardless of which app triggered it

These features solve both at the library level so any BurntToast consumer benefits — not just our use case.

Changes

File	What
src/Public/Submit-BTNotification.ps1	Added -CooldownSeconds param with lock file throttle logic
src/Public/New-BurntToastNotification.ps1	Added -CooldownSeconds passthrough, -AutoAppLogo switch, -AppLogoMap hashtable, mutual exclusion with -AppLogo
src/Private/Get-BTCallerAppIcon.ps1	New private function — process tree walk, icon extraction, caching, override map
Tests/Throttle.Tests.ps1	8 tests covering throttle behavior
Tests/Get-BTCallerAppIcon.Tests.ps1	10 tests covering auto logo detection
Tests/Advanced-Throttle.Tests.ps1	15 edge-case tests (stress, expiry, isolation, PNG validation, combined features)

Test plan

• 33 new Pester v5 tests added
• Full suite: 113/113 passing, zero regressions against existing 80 tests
• 20-call rapid-fire stress test — only 1 toast fires
• Cooldown expiry verified via backdated lock file
• Zero and negative CooldownSeconds handled correctly
• Lock file integrity: correct path, valid ISO 8601 timestamp
• Concurrent identifier isolation: independent cooldowns don't interfere
• Icon cache reuse: same path on repeated calls
• Cached icon validated as real PNG (magic bytes 89 50 4E 47)
• Combined throttle + AutoAppLogo interaction tested
• Graceful fallback when icon extraction fails or mapped path doesn't exist
• XML well-formedness verified with auto-detected icon