refactor(quota-viewer): 🔨 enhance credential sorting and cooldown display

refactor(usage): 🔨 sync request_count across quota group models

feat(usage): ✨ use request count for credential selection when failed requests consume quota

feat(quota-viewer): ✨ add quota and usage statistics viewer system

feat(antigravity): ✨ add credential availability tracking for models

feat(antigravity): ✨ add quota tracking with independent background jobs

refactor(core): 🔨 centralize path management for PyInstaller compatibility

feat(io): ✨ add fault-tolerant file operations with automatic recovery

Merge origin/main into feat/runtime-resilience - Resolve conflict in usage_manager.py by integrating runtime resilience with human-readable timestamps

feat(concurrency): ✨ add priority-based concurrency multipliers for credential tiers

feat(usage): ✨ add human-readable timestamp fields to usage data for debugging

fix(resilience): complete circuit breaker patterns per PR review

feat: add runtime resilience for file deletion survival

refactor(usage): 🔨 cache provider plugin instances to reduce redundant instantiation

feat(usage): ✨ implement per-model quota tracking with authoritative reset timestamps

feat(usage): ✨ add provider-specific rolling window usage tracking

feat(rotation): ✨ add sequential rotation mode with provider-specific quota parsing

feat(providers): ✨ implement credential tier initialization and persistence system

Merge branch 'Antigravity' of https://github.com/Mirrowel/LLM-API-Key-Proxy into fix/quota-exceeded-global-cooldown

fix(rotator): prevent quota errors from global cooldown

fix(logging): preserve full credential filenames in logs

feat(rotation): ✨ add configurable weighted random credential selection

feat(client): ✨ add credential prioritization system for tier-based model access

fix(auth): 🔨 tighten oauth refresh intervals, expand refresh buffers, improve logging and add iFlow docs

fix(core): improve error classification and prevent false key penalization

feat(core): enable configuration of maximum concurrent requests per key

refactor(core): 🔨 use static class attribute for provider skipping flag

feat(core): enable static model configuration and LiteLLM compatibility for custom providers

refactor(core): review fixes + improve error handling and execution logic

fix(core): stabilize streaming for custom providers and refine usage recording

fix(core): stabilize streaming for custom endpoints and eliminate initialization conflicts

refactor: improve model registration and usage manager robustness

fix(usage): initialize daily reset for new usage keys

refactor(rotator): randomize key selection and streamline daily stats reset

feat(core): implement deadline-driven request execution and resilient error handling

Fix(logging): enhance logging configuration and control

perf(rotator): prevent indefinite waits for API key acquisition

fix: Type import oopsie

feat: Add support for embeddings endpoint

feat: Handle API errors within streams and record usage

refactor: Remove file locking mechanism from usage data saving

feat: Enhance daily reset logic to ensure timezone-aware date handling

fix: Handle missing cooldown values in UsageManager to prevent key lockout type errors

feat: Update key release logic in RotatingClient and UsageManager to support model-specific tracking

feat: Enhance error classification and handling in UsageManager and error_handler for improved retry logic and cooldown management

feat: Enhance asynchronous handling in RotatingClient and UsageManager for improved error management and usage tracking

feat: Improve key acquisition logic in RotatingClient and UsageManager for better async handling and error management

feat: Enhance error handling in UsageManager to extract retry delay from multiple error message formats

feat: Refactor logging to use a dedicated logger across providers and enhance model retrieval with httpx

feat: Implement per-model API key cooldowns