feat: complete Rust port of claude-statusline

Port the entire 2236-line bash statusline script to Rust.
Implements all 25 sections, 3-phase layout engine (render, priority
drop, flex/justify), file-based caching with flock, 9-level terminal
width detection, trend sparklines, and deep-merge JSON config.

Release binary: 864K with LTO. Render time: <1ms warm.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

defaults.json

@@ -0,0 +1,271 @@
+{
+  "version": 1,
+  "global": {
+    "separator": " | ",
+    "justify": "space-between",
+    "vcs": "auto",
+    "cache_dir": "/tmp/claude-sl-{session_id}",
+    "responsive": true,
+    "breakpoints": {
+      "narrow": 60,
+      "medium": 100
+    },
+    "theme": "auto"
+  },
+  "colors": {
+    "dark": {
+      "success": "green",
+      "warning": "yellow",
+      "danger": "red",
+      "critical": "red bold",
+      "muted": "dim",
+      "accent": "cyan",
+      "highlight": "bold",
+      "info": "blue"
+    },
+    "light": {
+      "success": "green bold",
+      "warning": "yellow bold",
+      "danger": "red bold",
+      "critical": "red bold",
+      "muted": "dim",
+      "accent": "blue",
+      "highlight": "bold",
+      "info": "cyan"
+    }
+  },
+  "glyphs": {
+    "enabled": false,
+    "set": {
+      "separator": "",
+      "separator_alt": "",
+      "branch": "",
+      "dirty": "*",
+      "clean": "✓",
+      "ahead": "↑",
+      "behind": "↓",
+      "folder": "",
+      "clock": "",
+      "dollar": ""
+    },
+    "fallback": {
+      "separator": "|",
+      "separator_alt": "|",
+      "branch": "",
+      "dirty": "*",
+      "clean": "",
+      "ahead": "+",
+      "behind": "-",
+      "folder": "",
+      "clock": "",
+      "dollar": "$"
+    }
+  },
+  "presets": {
+    "standard": [
+      [
+        "model",
+        "provider",
+        "project",
+        "spacer",
+        "vcs"
+      ],
+      [
+        "context_bar",
+        "cost",
+        "lines_changed",
+        "duration",
+        "tools"
+      ]
+    ],
+    "dense": [
+      [
+        "model",
+        "provider",
+        "project",
+        "vcs",
+        "context_bar",
+        "cost",
+        "duration"
+      ]
+    ],
+    "verbose": [
+      [
+        "model",
+        "provider",
+        "project",
+        "vcs",
+        "beads"
+      ],
+      [
+        "context_bar",
+        "tokens_raw",
+        "cache_efficiency",
+        "cost",
+        "cost_velocity"
+      ],
+      [
+        "lines_changed",
+        "duration",
+        "tools",
+        "turns",
+        "load",
+        "version"
+      ]
+    ]
+  },
+  "layout": "verbose",
+  "sections": {
+    "model": {
+      "enabled": true,
+      "priority": 1
+    },
+    "provider": {
+      "enabled": true,
+      "priority": 2
+    },
+    "project": {
+      "enabled": true,
+      "priority": 1,
+      "truncate": {
+        "enabled": true,
+        "max": 30,
+        "style": "middle"
+      }
+    },
+    "vcs": {
+      "enabled": true,
+      "priority": 1,
+      "min_width": 8,
+      "prefer": "auto",
+      "show_ahead_behind": true,
+      "show_dirty": true,
+      "truncate": {
+        "enabled": true,
+        "max": 25,
+        "style": "right"
+      },
+      "ttl": {
+        "branch": 3,
+        "dirty": 5,
+        "ahead_behind": 30
+      }
+    },
+    "beads": {
+      "enabled": true,
+      "priority": 3,
+      "show_wip": true,
+      "show_wip_count": true,
+      "show_ready_count": true,
+      "show_open_count": true,
+      "show_closed_count": true,
+      "ttl": 30
+    },
+    "context_bar": {
+      "enabled": true,
+      "priority": 1,
+      "flex": true,
+      "min_width": 15,
+      "bar_width": 10,
+      "thresholds": {
+        "warn": 50,
+        "danger": 70,
+        "critical": 85
+      }
+    },
+    "context_usage": {
+      "enabled": false,
+      "priority": 2,
+      "capacity": 200000,
+      "thresholds": {
+        "warn": 50,
+        "danger": 70,
+        "critical": 85
+      }
+    },
+    "tokens_raw": {
+      "enabled": true,
+      "priority": 3,
+      "format": "{input} in/{output} out"
+    },
+    "cache_efficiency": {
+      "enabled": true,
+      "priority": 3
+    },
+    "cost": {
+      "enabled": true,
+      "priority": 1,
+      "thresholds": {
+        "warn": 5.00,
+        "danger": 8.00,
+        "critical": 10.00
+      }
+    },
+    "cost_velocity": {
+      "enabled": true,
+      "priority": 3
+    },
+    "token_velocity": {
+      "enabled": false,
+      "priority": 3
+    },
+    "cost_trend": {
+      "enabled": false,
+      "priority": 3,
+      "width": 8
+    },
+    "context_trend": {
+      "enabled": false,
+      "priority": 3,
+      "width": 8,
+      "thresholds": {
+        "warn": 50,
+        "danger": 70,
+        "critical": 85
+      }
+    },
+    "lines_changed": {
+      "enabled": true,
+      "priority": 2
+    },
+    "duration": {
+      "enabled": true,
+      "priority": 2
+    },
+    "tools": {
+      "enabled": true,
+      "priority": 2,
+      "min_width": 6,
+      "show_last_name": true,
+      "ttl": 2
+    },
+    "turns": {
+      "enabled": true,
+      "priority": 3,
+      "ttl": 2
+    },
+    "load": {
+      "enabled": true,
+      "priority": 3,
+      "ttl": 10
+    },
+    "version": {
+      "enabled": false,
+      "priority": 3
+    },
+    "time": {
+      "enabled": false,
+      "priority": 3,
+      "format": "%H:%M"
+    },
+    "output_style": {
+      "enabled": false,
+      "priority": 3
+    },
+    "hostname": {
+      "enabled": true,
+      "priority": 3
+    }
+  },
+  "custom": []
+}