feat: numa setup-phone — QR-based mobile DoT onboarding

Adds a CLI subcommand that generates a one-time mobileconfig profile
containing both the Numa local CA (as a com.apple.security.root payload)
and the DoT DNS settings, then serves it via a temporary HTTP server
and prints a scannable QR code in the terminal.

Flow:
  1. User runs `numa setup-phone` (no sudo needed)
  2. Detects current LAN IP, reads CA from /usr/local/var/numa/ca.pem
  3. Builds combined mobileconfig (CA trust + DoT)
  4. Renders QR code with qrcode crate (Unicode block characters)
  5. Serves the profile on port 8765, stays open until Ctrl+C
  6. Counts successful downloads (multi-device households)

Important caveat documented in instructions: even with the CA bundled
in the profile, iOS still requires the user to manually enable trust
in Settings → General → About → Certificate Trust Settings. Verified
on a real iPhone.

Stable PayloadIdentifiers/UUIDs ensure re-running replaces the
existing profile on iOS rather than accumulating duplicates.

- New module: src/setup_phone.rs (~270 lines)
- New CLI subcommand: `numa setup-phone`
- New dependency: qrcode = "0.14" (default-features = false)
- tokio "signal" feature added for Ctrl+C handling
- 3 unit tests: PEM stripping, mobileconfig generation, QR rendering

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -84,9 +84,9 @@ dependencies = [
 
 [[package]]
 name = "arc-swap"
-version = "1.9.1"
+version = "1.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6a3a1fd6f75306b68087b831f025c712524bcb19aad54e557b1129cfa0a2b207"
+checksum = "a07d1f37ff60921c83bdfc7407723bdefe89b44b98a9b772f225c8f9d67141a6"
 dependencies = [
  "rustversion",
 ]
@@ -522,6 +522,16 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "877a4ace8713b0bcf2a4e7eec82529c029f1d0619886d18145fea96c3ffe5c0f"
 
+[[package]]
+name = "errno"
+version = "0.3.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
+dependencies = [
+ "libc",
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "find-msvc-tools"
 version = "0.1.9"
@@ -757,9 +767,9 @@ checksum = "df3b46402a9d5adb4c86a0cf463f42e19994e3ee891101b1841f30a545cb49a9"
 
 [[package]]
 name = "hyper"
-version = "1.9.0"
+version = "1.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6299f016b246a94207e63da54dbe807655bf9e00044f73ded42c3ac5305fbcca"
+checksum = "2ab2d4f250c3d7b1c9fcdff1cece94ea4e2dfbec68614f7b87cb205f24ca9d11"
 dependencies = [
  "atomic-waker",
  "bytes",
@@ -772,6 +782,7 @@ dependencies = [
  "httpdate",
  "itoa",
  "pin-project-lite",
+ "pin-utils",
  "smallvec",
  "tokio",
  "want",
@@ -1145,6 +1156,7 @@ dependencies = [
  "hyper",
  "hyper-util",
  "log",
+ "qrcode",
  "rcgen",
  "reqwest",
  "ring",
@@ -1219,6 +1231,12 @@ version = "0.2.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"
 
+[[package]]
+name = "pin-utils"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
+
 [[package]]
 name = "plotters"
 version = "0.3.7"
@@ -1295,6 +1313,12 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "qrcode"
+version = "0.14.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d68782463e408eb1e668cf6152704bd856c78c5b6417adaee3203d8f4c1fc9ec"
+
 [[package]]
 name = "quinn"
 version = "0.11.9"
@@ -1674,6 +1698,16 @@ version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
 
+[[package]]
+name = "signal-hook-registry"
+version = "1.4.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4db69cba1110affc0e9f7bcd48bbf87b3f4fc7c61fc9155afd4c469eb3d6c1b"
+dependencies = [
+ "errno",
+ "libc",
+]
+
 [[package]]
 name = "simd-adler32"
 version = "0.3.9"
@@ -1833,14 +1867,15 @@ checksum = "1f3ccbac311fea05f86f61904b462b55fb3df8837a366dfc601a0161d0532f20"
 
 [[package]]
 name = "tokio"
-version = "1.51.1"
+version = "1.50.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f66bf9585cda4b724d3e78ab34b73fb2bbaba9011b9bfdf69dc836382ea13b8c"
+checksum = "27ad5e34374e03cfffefc301becb44e9dc3c17584f414349ebe29ed26661822d"
 dependencies = [
  "bytes",
  "libc",
  "mio",
  "pin-project-lite",
+ "signal-hook-registry",
  "socket2",
  "tokio-macros",
  "windows-sys 0.61.2",
@@ -1848,9 +1883,9 @@ dependencies = [
 
 [[package]]
 name = "tokio-macros"
-version = "2.7.0"
+version = "2.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "385a6cb71ab9ab790c5fe8d67f1645e6c450a7ce006a33de03daa956cf70a496"
+checksum = "5c55a2eff8b69ce66c84f85e1da1c233edc36ceb85a2058d11b0d6a3c7e7569c"
 dependencies = [
  "proc-macro2",
  "quote",