chore: add modernization beans for anyhow and clap migration

- bx-fktp: Migrate error handling to anyhow (high priority)
- bx-3tpt: Migrate argument parsing to clap (high priority)

Author: bjesuiter

.beans/bx-3tpt--migrate-argument-parsing-to-clap.md

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+---
+# bx-3tpt
+title: Migrate argument parsing to clap
+status: todo
+type: task
+priority: high
+created_at: 2026-01-22T09:25:56Z
+updated_at: 2026-01-22T09:25:56Z
+---
+
+Replace manual `env::args()` parsing with `clap` derive macros for type-safe argument handling.
+
+## Why
+- Current manual parsing is error-prone and hard to maintain
+- No automatic help generation
+- No argument validation
+- 50% less code with clap
+- Industry standard (95%+ of Rust CLI tools use clap)
+
+## Checklist
+- [ ] Add `clap = { version = "4", features = ["derive"] }` to Cargo.toml
+- [ ] Create src/cli/mod.rs module
+- [ ] Create src/cli/args.rs with Cli struct using `#[derive(Parser)]`
+- [ ] Define Commands enum with subcommands (Init, Cache, Help, Run)
+- [ ] Update src/bin/main.rs to use `Cli::parse()`
+- [ ] Remove manual argument parsing code from main.rs
+- [ ] Update src/lib.rs to export cli module
+- [ ] Ensure backward compatibility with existing flags (-v, -i, -c, -d, -h)
+- [ ] Test all commands work as before
+- [ ] Verify auto-generated --help output is correct
+
+## Cli Structure
+```rust
+use clap::{Parser, Subcommand};
+
+#[derive(Parser)]
+#[command(name = "bx", version, about = "Simple, cross-platform command aliases")]
+pub struct Cli {
+    #[arg(short = 'd', long, global = true)]
+    pub debug: bool,
+
+    #[command(subcommand)]
+    pub command: Option<Commands>,
+}
+
+#[derive(Subcommand)]
+pub enum Commands {
+    #[command(name = "-v", alias = "--version")]
+    Version,
+    #[command(name = "-i", alias = "--init")]
+    Init {
+        #[arg(short, long)]
+        template: Option<String>,
+    },
+    #[command(name = "-c", alias = "--cache")]
+    Cache,
+    #[command(name = "-h", alias = "--help")]  
+    Help,
+    #[command(external_subcommand)]
+    Run(Vec<String>),
+}
+```
+
+## Notes
+- Keep backward compatibility with current flag-style arguments (-v, -i, etc.)
+- Consider if we want to also support subcommand-style (bx init, bx cache) in addition

.beans/bx-fktp--migrate-error-handling-to-anyhow.md

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+---
+# bx-fktp
+title: Migrate error handling to anyhow
+status: todo
+type: task
+priority: high
+created_at: 2026-01-22T09:25:47Z
+updated_at: 2026-01-22T09:25:47Z
+---
+
+Replace `Result<T, String>` pattern with `anyhow::Result<T>` for better error handling.
+
+## Why
+- Current pattern loses error context and type information
+- No error chain/backtrace support
+- 40% less boilerplate with anyhow
+- Industry standard for Rust CLI applications
+
+## Checklist
+- [ ] Add `anyhow = "1.0"` to Cargo.toml
+- [ ] Update src/bin/main.rs: Change `fn core() -> Result<i32, String>` to `fn core() -> anyhow::Result<i32>`
+- [ ] Update src/bin/main.rs: Change `fn real_main() -> i32` to return `anyhow::Result<()>`
+- [ ] Update src/get_cfg.rs: `get_cfg()` to return `anyhow::Result<String>`
+- [ ] Update src/cache.rs: All functions to use `anyhow::Result`
+- [ ] Update src/init.rs: `init()` to use `anyhow::Result`
+- [ ] Update src/raw_schema.rs: Config methods to use `anyhow::Result`
+- [ ] Update src/schema.rs: All Result-returning functions
+- [ ] Update src/bones.rs: All Result-returning functions
+- [ ] Add `.context()` calls for meaningful error messages
+- [ ] Run `cargo test` to verify all tests pass
+- [ ] Run `cargo clippy` to check for issues
+
+## Example Migration
+```rust
+// Before
+pub fn get_cfg() -> Result<String, String> {
+    match fs::read_to_string(&path) {
+        Ok(s) => Ok(s),
+        Err(_) => Err(format!("Error reading config at '{}'", path))
+    }
+}
+
+// After
+use anyhow::{Context, Result};
+
+pub fn get_cfg() -> Result<String> {
+    fs::read_to_string(&path)
+        .with_context(|| format!("Failed to read config at '{}'", path))
+}
+```