Reorganize into multi-workspace structure, simplify examples, remove defmt

[aq1018]

Summary

• Reorganize flat crate layout into three independent workspaces: lib/ (core + protocol), ch32/ (hal + boot + app), cli/
• Rename tinyboot package to tinyboot-core, tinyboot-cli to tinyboot
• Remove defmt from all library crates; delete tinyboot-macros crate entirely
• Merge boot/app examples into a single workspace at examples/ch32/v003/
• Establish standardized linker region contract (CODE, BOOT, APP, META, RAM) — all __tb_* symbols derived from regions in crate linker scripts, no magic numbers in memory.x
• Replace hardcoded flash constants with linker symbols; Storage and BootCtl now use Default (read geometry from linker symbols at init)
• new_app() takes zero parameters
• run() convenience function takes just a transport — wires up Storage/BootMetaStore/BootCtl internally
• Add prelude module to boot crate
• Collapse 16 per-chip memory_x files to 4 (all V003 chips have identical flash/RAM)
• Reduce user-flash bootloader reservation from 8KB to 2KB (binary is ~1.9KB)
• Update all READMEs, CI, pre-commit, .gitignore

Boot example (entire main.rs)

tinyboot_ch32_boot::boot_version!();
use tinyboot_ch32_boot::prelude::*;

fn main() -> ! {
    let transport = Usart::new(&UsartConfig {
        duplex: Duplex::Full,
        baud: BaudRate::B115200,
        pclk: 8_000_000,
        mapping: UsartMapping::Usart1Remap0,
        rx_pull: Pull::None,
        tx_en: None,
    });
    tinyboot_ch32_boot::run(transport);
}

App example (init)

let mut app = tinyboot_ch32_app::new_app(); // zero args, all from linker symbols
app.confirm();

Binary sizes (CH32V003F4P6, release)

Binary	Flash	Budget	Free
boot system-flash	1798 B	1920 B	122 B
boot user-flash	1888 B	2048 B	160 B
app system-flash	3980 B	16320 B	12340 B
app user-flash	3996 B	14272 B	10276 B