feat: replace inotify watch path with fsnotify and clean up related tooling/docs (#204)

* Plan fsnotify migration and docs updates

Co-authored-by: Belphemur <197810+Belphemur@users.noreply.github.com>

* Refactor watch mode to fsnotify and add agent docs

Co-authored-by: Belphemur <197810+Belphemur@users.noreply.github.com>

* Fix errcheck violations in command and converter tests

Co-authored-by: Belphemur <197810+Belphemur@users.noreply.github.com>

* Complete validation for fsnotify and lint fixes

Co-authored-by: Belphemur <197810+Belphemur@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Belphemur <197810+Belphemur@users.noreply.github.com>

docs/project-overview.md

@@ -0,0 +1,27 @@
+# Project Overview
+
+CBZOptimizer is a Go CLI that optimizes comic archives (`.cbz` and `.cbr`) by converting page images to modern formats (currently WebP).
+
+## High-level flow
+
+1. Load chapters from archive files.
+2. Decode pages and optionally split oversized pages.
+3. Convert images with the selected converter.
+4. Write optimized output as CBZ.
+
+## Main components
+
+- `cmd/cbzoptimizer`: CLI commands and flag wiring (`optimize`, `watch`).
+- `internal/cbz`: archive loading and writing.
+- `internal/manga`: chapter and page domain models.
+- `internal/utils`: orchestration utilities (`optimize` flow and file helpers).
+- `pkg/converter`: converter abstraction and format implementations.
+
+## Watch mode
+
+`watch` monitors a directory tree for archive file changes and runs optimization automatically.
+
+## Key runtime requirements
+
+- Go 1.25+
+- WebP encoder setup via `cmd/encoder-setup` for WebP conversion tests and runtime support.