port habitica integration from JS to Rust

The old JS ppc repo had a working habitica integration. This ports all
that functionality into the new Rust-based marts package so it can run
natively without the Deno/JS runtime dependency.

Changes:
- habitica.rs: make api_request public, add get_tasks() and delete_task()
  convenience methods, register config opts
- c2vi/mod.rs: full rewrite implementing all 9 CLI commands (bed,
  clearTodos, listTodos, buyHealthPotion, addActionItems, skip, dumpLog,
  listDailies, printTask) with SQLite persistence via rusqlite
- lib.rs: wire c2vi module into marts exports
- ppc main.rs: register c2vi part at startup
- Cargo.toml: add rusqlite dependency with bundled feature

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

Cargo.lock

@@ -2728,6 +2728,18 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "fallible-iterator"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2acce4a10f12dc2fb14a218589d4f1f62ef011b2d0cc4b3cb1bba8e94da14649"
+
+[[package]]
+name = "fallible-streaming-iterator"
+version = "0.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7360491ce676a36bf9bb3c56c1aa791658183a54d2744120f27285738d90465a"
+
 [[package]]
 name = "fastrand"
 version = "2.3.0"
@@ -3483,6 +3495,15 @@ dependencies = [
  "foldhash",
 ]
 
+[[package]]
+name = "hashlink"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6ba4ff7128dee98c7dc9794b6a411377e1404dba1c97deb8d1a55297bd25d8af"
+dependencies = [
+ "hashbrown 0.14.5",
+]
+
 [[package]]
 name = "headers"
 version = "0.3.9"
@@ -4260,6 +4281,17 @@ dependencies = [
  "redox_syscall 0.7.0",
 ]
 
+[[package]]
+name = "libsqlite3-sys"
+version = "0.28.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c10584274047cb335c23d3e61bcef8e323adae7c5c8c760540f73610177fc3f"
+dependencies = [
+ "cc",
+ "pkg-config",
+ "vcpkg",
+]
+
 [[package]]
 name = "libxdo"
 version = "0.6.0"
@@ -4430,6 +4462,7 @@ dependencies = [
  "futures",
  "mize",
  "reqwest 0.13.2",
+ "rusqlite",
  "rustyscript",
  "serde",
  "serde_json",
@@ -6036,6 +6069,20 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "rusqlite"
+version = "0.31.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b838eba278d213a8beaf485bd313fd580ca4505a00d5871caeb1457c55322cae"
+dependencies = [
+ "bitflags 2.11.0",
+ "fallible-iterator",
+ "fallible-streaming-iterator",
+ "hashlink",
+ "libsqlite3-sys",
+ "smallvec",
+]
+
 [[package]]
 name = "rustc-hash"
 version = "1.1.0"