Add verify-canfetch flag and git2 integration for repo accessibility checks

```
│  Agent powering down. Goodbye!
│
│  Interaction Summary
│  Session ID:                 9010bd84-1fb3-489d-ae48-89d5e7570b34
│  Tool Calls:                 26 ( ✓ 25 x 1 )
│  Success Rate:               96.2%
│  User Agreement:             96.2% (26 reviewed)
│  Code Changes:               +116 -23
│
│  Performance
│  Wall Time:                  59m 38s
│  Agent Active:               9m 53s
│    » API Time:               4m 22s (44.1%)
│    » Tool Time:              5m 31s (55.9%)
│
│
│  Model Usage                 Reqs   Input Tokens   Cache Reads  Output Tokens
│  ────────────────────────────────────────────────────────────────────────────
│  gemini-2.5-flash-lite          6         10,569             0            596
│  gemini-3-pro-preview          23        114,081       377,312         10,537
│  gemini-3-flash-preview         7         88,472        83,196            436
│
│  Savings Highlight: 460,508 (68.4%) of input tokens were served from the cache, reducing costs.
```

Cargo.lock

@@ -360,11 +360,27 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "git2"
+version = "0.19.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b903b73e45dc0c6c596f2d37eccece7c1c8bb6e4407b001096387c63d0d93724"
+dependencies = [
+ "bitflags",
+ "libc",
+ "libgit2-sys",
+ "log",
+ "openssl-probe 0.1.6",
+ "openssl-sys",
+ "url",
+]
+
 [[package]]
 name = "gitea_mirror"
 version = "0.1.0"
 dependencies = [
  "clap",
+ "git2",
  "reqwest",
  "serde",
  "serde_json",
@@ -702,6 +718,46 @@ version = "0.2.179"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c5a2d376baa530d1238d133232d15e239abad80d05838b4b59354e5268af431f"
 
+[[package]]
+name = "libgit2-sys"
+version = "0.17.0+1.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10472326a8a6477c3c20a64547b0059e4b0d086869eee31e6d7da728a8eb7224"
+dependencies = [
+ "cc",
+ "libc",
+ "libssh2-sys",
+ "libz-sys",
+ "openssl-sys",
+ "pkg-config",
+]
+
+[[package]]
+name = "libssh2-sys"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "220e4f05ad4a218192533b300327f5150e809b54c4ec83b5a1d91833601811b9"
+dependencies = [
+ "cc",
+ "libc",
+ "libz-sys",
+ "openssl-sys",
+ "pkg-config",
+ "vcpkg",
+]
+
+[[package]]
+name = "libz-sys"
+version = "1.1.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "15d118bbf3771060e7311cc7bb0545b01d08a8b4a7de949198dec1fa0ca1c0f7"
+dependencies = [
+ "cc",
+ "libc",
+ "pkg-config",
+ "vcpkg",
+]
+
 [[package]]
 name = "litemap"
 version = "0.8.1"
@@ -773,12 +829,30 @@ version = "1.70.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "384b8ab6d37215f3c5301a95a4accb5d64aa607f1fcb26a11b5303878451b4fe"
 
+[[package]]
+name = "openssl-probe"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d05e27ee213611ffe7d6348b942e8f942b37114c00cc03cec254295a4a17852e"
+
 [[package]]
 name = "openssl-probe"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9f50d9b3dabb09ecd771ad0aa242ca6894994c130308ca3d7684634df8037391"
 
+[[package]]
+name = "openssl-sys"
+version = "0.9.111"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "82cab2d520aa75e3c58898289429321eb788c3106963d0dc886ec7a5f4adc321"
+dependencies = [
+ "cc",
+ "libc",
+ "pkg-config",
+ "vcpkg",
+]
+
 [[package]]
 name = "parking_lot"
 version = "0.12.5"
@@ -820,6 +894,12 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
 
+[[package]]
+name = "pkg-config"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7edddbd0b52d732b21ad9a5fab5c704c14cd949e5e9a1ec5929a24fded1b904c"
+
 [[package]]
 name = "potential_utf"
 version = "0.1.4"
@@ -1037,7 +1117,7 @@ version = "0.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "612460d5f7bea540c490b2b6395d8e34a953e52b491accd6c86c8164c5932a63"
 dependencies = [
- "openssl-probe",
+ "openssl-probe 0.2.0",
  "rustls-pki-types",
  "schannel",
  "security-framework",
@@ -1646,6 +1726,12 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ba73ea9cf16a25df0c8caa16c51acb937d5712a8429db78a3ee29d5dcacd3a65"
 
+[[package]]
+name = "vcpkg"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "accd4ea62f7bb7a82fe23066fb0957d48ef677f6eeb8215f372f52e48bb32426"
+
 [[package]]
 name = "walkdir"
 version = "2.5.0"