feat: move standard note scripts into standard library

[Farukest]

Summary

Move note script logic from standalone files in note_scripts/ directory to miden::standards::notes namespace modules. This enables dynamic access to script roots via procref instead of hardcoding values.

For context see #2156 and #2188.

Changes:

• Add new modules under standards/notes/: p2id, p2ide, swap, burn, mint
• Each module contains a pub proc main with the script logic
• Original note script files now serve as minimal wrappers calling exec.<note>::main

Benefits

• Script roots accessible via procref.p2id::main (no more hardcoded constants)
• Note script files reduced from ~100+ lines to 5 lines each
• Opens possibility for future note constructors (separate PR)

Test plan

• cargo build -p miden-standards passes
• cargo test -p miden-standards passes (52 tests)
• Note script integration tests pass (27 tests: p2id, p2ide, swap, mint, burn)

Closes #2243