[DRAFT] Rewrite DragonRunner in Rust?

[JustinMeimar]

Motivations:

1. Deploying dragon-runner on the lab machines had some issues.
   • Ancient python version (3.8) we had to conform to.
   • Error pronechmod in the CMPUT415 users' local python packages to get
     the binary to unlock (now we have a single statically linked executable.)
2. Fuses gazbolt into this project.
3. Opus 4.6 let me drive this in a few hours.

Refactors:

• Full rewrite of dragon-runner from python to rust driven by Claude Opus 4.6
• Simplified toolchain config json (exe/args instead of stepName/executablePath/arguments/output).
  The lingering config files on the lab machines will need to be updated (along with the executable.)
• proc-macro logging system replacing scattered print statements
• Toolchain runner rewritten as try_fold pipeline rather than imperative hair ball.
• Updated README to reflect changes.

Fixes:

• memcheck mode is now decoupled from valgrind-specific configs. This was a hazard last year,
  running memcheck w/o the specific config gave false positives.
• All grading scripts now driven from a single key system. We can fill out once with each students
  information at the beginning of a semester, then automatically drive cloning, building, testfile
  pruning, config synthesis, etc, which require some alignment with student info.

Features:

• Parallel test execution within subpackages.
• Serve mode for producing a compiler explorer for any config, using a light-weigt HTML and JS single
  files in lieu of "Gazbolt" (not sure if we want to bring a svelte dependecy into this project.)
• SKIP directive for skipping individual test files. (closes [FEAT] Explicit Skip Rule #18)
• --full-path flag to log absolute test paths on failure. (closes [FEAT] Print full failing test paths #19)

Todo:

• Sleep on it... I'm probably forgetting something.