feat: implement MVP foundation — quote, history, provider abstraction

- Cargo init with clap, ureq, serde, comfy-table, owo-colors, thiserror
- Module structure: cli/, api/, output/, cache, config, error
- MarketDataProvider trait abstraction (swappable providers)
- Yahoo Finance provider via query2 endpoint (no crumb needed)
  - Retry with exponential backoff + jitter on 429
  - chartPreviousClose fallback for change calculation
- Symbol resolution: BBCA → BBCA.JK
- Output layer: table (comfy-table + owo-colors) and JSON
- Config loading foundation (TOML + env + defaults)
- Commands: stocks quote, stocks history, version, completions
- 9 tests (unit + integration) with mock provider
- Verified: cargo build, clippy -D warnings, cargo test all green

flake.lock

@@ -0,0 +1,82 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1772674223,
+        "narHash": "sha256-/suKbHSaSmuC9UY7G0VRQ3aO+QKqxAQPQ19wG7QNkF8=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "66d9241e3dc2296726dc522e62dbfe89c7b449f3",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs",
+        "rust-overlay": "rust-overlay"
+      }
+    },
+    "rust-overlay": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1772679930,
+        "narHash": "sha256-FxYmdacqrdDVeE9QqZKTIpNLjv2B8GSKssgwlZuTR98=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "9b741db17141331fdb26270a1b66b81be8be9edd",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}