Initialize project skeleton with CLI and documentation

Add initial project structure including:
- Go module with Cobra CLI dependency
- Root command and main entrypoint
- Basic documentation (README, AGENTS.md, architecture, decisions,
  development, roadmap)
- Configuration example and gitignore
- Tool version management with mise
- Comprehensive project rules and conventions

docs/README.md

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+# Docs
+
+| File | Content |
+|------|---------|
+| `architecture.md` | Module layout, package boundaries |
+| `decisions.md` | Technical decisions (ADR) |
+| `roadmap.md` | Feature progress and status |
+| `development.md` | Build, test, debug workflow |

docs/architecture.md

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+# Architecture
+
+## Code Layout
+
+```
+main.go              — entrypoint, calls cmd.Execute()
+cmd/                  — cobra commands (root + subcommands)
+internal/             — private application packages
+docs/                 — project documentation
+```
+
+## Packages
+
+| Package | Purpose | Status |
+|---------|---------|--------|
+| `cmd` | CLI command definitions | ✅ skeleton |
+| `internal/config` | Configuration loading and parsing | ⬜ planned |
+| `internal/controllers` | HTTP request handlers | ⬜ planned |
+| `internal/auth` | Authentication (JWT) | ⬜ planned |
+| `internal/storage` | File storage abstraction | ⬜ planned |
+
+Add new rows as packages are created.

docs/decisions.md

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+# Technical Decisions
+
+Record significant technical decisions as they are made. Use the format below.
+
+## Template
+
+```
+## YYYY-MM-DD: Title
+
+**Context**: Why this decision was needed.
+
+**Decision**: What was decided.
+
+**Consequences**: What this means for the project.
+```
+
+## Decisions
+
+*(None yet. Add entries as decisions are made.)*

docs/development.md

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+# Development
+
+## Prerequisites
+
+- Go 1.26.2 (pinned in `mise.toml`)
+- `mise` (https://mise.jdx.dev) — run `mise install` to install toolchain
+
+## Build
+
+```bash
+go build ./...
+go build -o mygo .
+```
+
+## Test
+
+```bash
+go test ./...
+go test -v -run TestName ./internal/...
+```
+
+## Lint & Format
+
+```bash
+go vet ./...
+go fmt ./...
+```
+
+## Config
+
+Server config is in `config.yaml` (symlink to `config.example.yaml` in development environment).
+
+```
+server:
+    host: 0.0.0.0
+    port: 10086
+```

docs/roadmap.md

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+# Roadmap
+
+See `README.md` for high-level feature list. This file tracks detailed progress.
+
+## v0
+
+| Feature | Status | Notes |
+|---------|--------|-------|
+| CLI config management | ⬜ planned | |
+| JWT authentication | ⬜ planned | |
+| File upload/download/manage APIs | ⬜ planned | |
+| Admin endpoints | ⬜ planned | |
+| WebDAV | ⬜ planned | |
+
+## Future
+
+| Feature | Status | Notes |
+|---------|--------|-------|
+| Image server | ⬜ planned | |
+| Pastebin & code snippets | ⬜ planned | |
+| S3 storage backend | ⬜ planned | |
+| Nextcloud-compatible API | ⬜ planned | |
+
+Update status after completing related work.