docs: convert docs to markdown, add TUI guide, fix sidebar layout

docs/package.json

@@ -12,5 +12,8 @@
     "@sveltejs/kit": "^2.20.8",
     "svelte": "^5.28.2",
     "vite": "^6.3.5"
+  },
+  "devDependencies": {
+    "mdsvex": "^0.12.7"
   }
 }

docs/src/app.css

@@ -234,6 +234,9 @@ aside nav {
   display: flex;
   flex-direction: column;
   height: auto;
+  max-width: none;
+  margin: 0;
+  padding: 0;
 }
 
 .sidebar-section {
@@ -297,17 +300,31 @@ main {
 @media (min-width: 769px) {
   aside {
     transform: translateX(0);
-    position: sticky;
+    position: fixed;
+    left: 0;
     top: var(--header-height);
     height: calc(100vh - var(--header-height));
+    z-index: 50;
   }
 
   .sidebar-overlay {
     display: none !important;
   }
 
+  .layout {
+    max-width: none;
+    margin: 0;
+    padding-left: var(--sidebar-width);
+  }
+
   main {
-    margin-left: var(--sidebar-width);
+    margin-left: 0;
+  }
+
+  nav {
+    max-width: none;
+    margin: 0;
+    padding-left: var(--sidebar-width);
   }
 }
 

docs/src/lib/layouts/MarkdownLayout.svelte

@@ -0,0 +1,25 @@
+<script lang="ts">
+  let {
+    children,
+    title = "subtrack",
+    description = "",
+  }: {
+    children: import("svelte").Snippet
+    title?: string
+    description?: string
+  } = $props()
+</script>
+
+<svelte:head>
+  <title>{title === "subtrack" ? "subtrack" : `${title} — subtrack`}</title>
+  {#if description}
+    <meta name="description" content={description} />
+  {/if}
+</svelte:head>
+
+<div class="docs">
+  {#if title !== "subtrack"}
+    <h1>{title}</h1>
+  {/if}
+  {@render children()}
+</div>

docs/src/routes/+layout.svelte

@@ -34,6 +34,7 @@
       title: "Guides",
       items: [
         { href: "/guides", label: "Usage Guides" },
+        { href: "/tui", label: "Interactive TUI" },
         { href: "/data", label: "Data & Storage" },
         { href: "/configuration", label: "Configuration" },
       ],

docs/src/routes/commands/+page.md

@@ -0,0 +1,142 @@
+---
+title: Commands
+description: Full reference for all subtrack CLI commands.
+---
+
+subtrack provides six commands. Most support both interactive and non-interactive modes.
+
+## `list`
+
+Lists all subscriptions in a formatted table. Subscriptions are grouped by currency by default, with a subtotal row per group.
+
+| Option | Description |
+|--------|-------------|
+| `-c, --currency <C>` | Convert all prices to the given currency using live exchange rates |
+
+### Examples
+
+```bash
+# List all subscriptions (grouped by currency)
+subtrack list
+
+# Convert all prices to JPY
+subtrack list --currency JPY
+```
+
+When `--currency` is used, all prices are converted to the target currency (fetched from [open.er-api.com](https://open.er-api.com)) and displayed as a single group with a grand total.
+
+## `add`
+
+Adds a new subscription. Without flags, prompts for all fields interactively. Providing all flags skips prompts entirely (useful for scripts).
+
+| Option | Description |
+|--------|-------------|
+| `--name <name>` | Subscription name (max 100 characters) |
+| `--price <price>` | Payment amount — integer, non-negative, max 99,999,999 |
+| `--currency <C>` | Currency code. Supported: JPY, USD, EUR, GBP, AUD, CAD, KRW, CNY, SGD, HKD |
+| `--cycle <cycle>` | Billing cycle. One of: weekly, bi-weekly, monthly, quarterly, semi-annual, yearly |
+| `--tags <tags>` | Comma-separated tags (max 10 tags, each max 50 characters) |
+
+### Examples
+
+```bash
+# Interactive mode
+subtrack add
+
+# Fully non-interactive (skips confirmation)
+subtrack add \
+  --name Spotify \
+  --price 980 \
+  --currency JPY \
+  --cycle monthly \
+  --tags music
+
+# Partial flags — missing fields are prompted
+subtrack add --name Netflix
+
+# Tags with existing tag autocomplete
+subtrack add --name "AWS" --price 50 --currency USD --cycle monthly
+```
+
+## `delete`
+
+Shows an interactive checkbox list of all subscriptions. Select one or more to delete. Confirmation is required before deletion.
+
+<div class="callout warning">
+  <strong>⚠ Note:</strong> The <code>delete</code> command is always interactive. There is no non-interactive mode.
+</div>
+
+### Example
+
+```bash
+subtrack delete
+```
+
+## `payment [period]`
+
+Calculates and displays how much you pay over a given billing period. All subscriptions are automatically converted to the target period based on their billing cycle.
+
+The `period` argument defaults to `monthly`. Valid values:
+
+| Period | Alias |
+|--------|-------|
+| `weekly` | per week |
+| `bi-weekly` | per two weeks |
+| `monthly` | per month (default) |
+| `quarterly` | per 3 months |
+| `semi-annual` | per 6 months |
+| `yearly` | per year |
+
+| Option | Description |
+|--------|-------------|
+| `-c, --currency <C>` | Convert all prices to the given currency using live exchange rates |
+
+### Examples
+
+```bash
+# Monthly total (default)
+subtrack payment
+
+# Yearly total
+subtrack payment yearly
+
+# Weekly total in JPY
+subtrack payment weekly --currency JPY
+```
+
+When `--currency` is used, the total is displayed as a single amount in the target currency. Without it, totals are grouped by currency.
+
+If exchange rates cannot be fetched (e.g. offline), the command falls back to per-currency display without conversion.
+
+## `tags <taglist...>`
+
+Filters and displays subscriptions that have **all** specified tags (AND logic).
+
+### Examples
+
+```bash
+# Subscriptions tagged with "music"
+subtrack tags music
+
+# Subscriptions tagged with both "music" AND "video"
+subtrack tags music video
+
+# Subscriptions tagged with "entertainment", "video", and "kids"
+subtrack tags entertainment video kids
+```
+
+## `backup <destination>`
+
+Creates a timestamped backup of the SQLite database in the specified directory. The backup filename follows the format `subtrack_YYYYMMDD_HHmmss.db`.
+
+If the destination does not exist or is not a directory, the command exits with an error. The backup will not overwrite existing files (exclusive create).
+
+### Examples
+
+```bash
+# Backup to current directory
+subtrack backup .
+
+# Backup to ~/backups
+subtrack backup ~/backups
+```