Add Tiger Style algorithms - 9 expert implementations with 102 tests

[copyleftdev]

Overview

This PR adds a comprehensive Tiger Style algorithm collection to showcase expert-level implementations following TigerBeetle's Tiger Style principles.

What's Included

9 Production-Quality Implementations (102 tests):

1. ✅ time_simulation.zig (7 tests) - Deterministic time simulation framework
2. ✅ merge_sort_tiger.zig (14 tests) - Zero-recursion merge sort
3. ✅ knapsack_tiger.zig (12 tests) - 0/1 Knapsack with heavy assertions
4. ✅ ring_buffer.zig (15 tests) - Bounded FIFO queue with fail-fast
5. ✅ raft_consensus.zig (12 tests) - Raft distributed consensus
6. ✅ two_phase_commit.zig (9 tests) - Two-phase commit protocol
7. ✅ vsr_consensus.zig (11 tests) - Viewstamped Replication (TigerBeetle's actual consensus)
8. ✅ robin_hood_hash.zig (12 tests) - Cache-efficient hash table with Robin Hood hashing
9. ✅ skip_list.zig (10 tests) - Probabilistic ordered map (foundation for LSM trees)

Tiger Style Principles

All implementations follow rigorous Tiger Style discipline:

• ✅ No recursion - Explicit iteration with bounded loops
• ✅ Heavy assertions - Minimum 2 per function, often 5-10+
• ✅ Explicit types - u32/u64/i32 everywhere (never usize)
• ✅ Bounded operations - Every loop has provable upper bounds
• ✅ Fail-fast - Invalid inputs error immediately
• ✅ Zero technical debt - Production-ready from day one

Testing

All 102 tests pass:

zig test tiger_style/time_simulation.zig       #  7 tests ✓
zig test tiger_style/merge_sort_tiger.zig      # 14 tests ✓
zig test tiger_style/knapsack_tiger.zig        # 12 tests ✓
zig test tiger_style/ring_buffer.zig           # 15 tests ✓
zig test tiger_style/raft_consensus.zig        # 12 tests ✓
zig test tiger_style/two_phase_commit.zig      #  9 tests ✓
zig test tiger_style/vsr_consensus.zig         # 11 tests ✓
zig test tiger_style/robin_hood_hash.zig       # 12 tests ✓
zig test tiger_style/skip_list.zig             # 10 tests ✓

Why This Matters

This showcases:

• Advanced algorithms (consensus, distributed systems, data structures)
• Production-quality code (inspired by TigerBeetle database)
• Rigorous engineering discipline
• Educational value for learning robust system design

Files Changed

• Added tiger_style/ directory with 9 implementations + README
• Updated DIRECTORY.md to include Tiger Style section

Total: 4,351 lines of production-quality code

[kassane]

Hi @copyleftdev,
Add all new algorithms in runall.zig to run tests.

[copyleftdev]

@kassane updated