feat(json): add TOON encoding to preserve all JSON values (#621, #827)

[voska]

Summary

• json_cmd and curl_cmd now try TOON encoding before compact/schema extraction
• TOON preserves ALL values with 22-59% fewer bytes than JSON — LLMs get data they can reason over instead of type placeholders (benchmarks: 76.4% accuracy vs JSON's 75.0% across 4 models, 5,016 calls)
• 16 KB byte budget (~4,000 tokens) with line-boundary truncation for large datasets
• RTK_NO_TOON=1 disables, falling back to existing behavior
• New toon_convert module: 1 public function, 9 tests

Before (6-item array):

[{
    id: 1
    name: "alice"
    role: "admin"
  }, ... +5 more]

After:

[6]{id,name,role}:
  1,alice,admin
  2,bob,user
  3,charlie,user
  4,diana,admin
  5,eve,user
  6,frank,user

142 bytes / 0% data → 120 bytes / 100% data.

Addresses #621 (JSON filter strips all values), #827 (silent truncation trust loss), #690 (over-compression causing 3x agent cost), #488 (no middle ground between aggressive and off).

Test plan

• cargo fmt --all && cargo clippy --all-targets && cargo test — 1123 passed, 0 warnings
• Binary size unchanged: 5.7 MB → 5.7 MB
• Manual: echo '[6 items]' | rtk json - shows all items as TOON
• Manual: RTK_NO_TOON=1 restores old compact behavior
• Manual: --schema mode unchanged
• UTF-8 boundary safety verified (multi-byte chars near budget)
• No-newline truncation path verified (wide headers)

[CLAassistant]

All committers have signed the CLA.

[aeppling]

Hey

We are cleaning up the codebase and improving the project structure for better onboarding. As part of this effort, PR #826 reorganizes src/ from a flat layout into subfolders.

No logic changes — only file moves and import path updates.

What you need to do

Rebase your branch on develop when receiving this comment:

git fetch origin && git rebase origin/develop

Git detects renames automatically. If you get import conflicts, update the paths:

use crate::git;        // now: use crate::cmds::git::git;
use crate::tracking;   // now: use crate::core::tracking;
use crate::config;     // now: use crate::core::config;
use crate::init;       // now: use crate::hooks::init;
use crate::gain;       // now: use crate::analytics::gain;

Need help rebasing? Tag @aeppling

[voska]

Rebased and moved toon_convert.rs into src/core/. Import paths updated, 1,132 tests pass. Thanks @aeppling.