Rewrite Initium from Go to Rust

Complete reimplementation of all 6 subcommands in Rust:
- wait-for (TCP + HTTP/HTTPS with retries, backoff, jitter)
- migrate (command exec with lock file idempotency)
- seed (command exec with structured logging)
- render (envsubst + Jinja2 templates via minijinja)
- fetch (HTTP fetch with auth, TLS, retry)
- exec (arbitrary command with workdir support)
Key dependencies: clap, ureq+rustls, serde_json, minijinja, regex, chrono
36 unit tests covering: logging, retry, safety, render modules
All tests passing.
Binary size comparison (release, stripped, musl-linked):
- Go binary (scratch): ~7.4 MB
- Rust binary (scratch): ~1.8 MB (76% reduction)
Docker image (scratch + binary + CA certs): 1.83 MB total

Author: mikkeldamsgaard

.dockerignore

@@ -0,0 +1,9 @@
+target/
+.git/
+bin/
+*.md
+docs/
+examples/
+charts/
+tests/
+.github/

.gitignore

@@ -1,17 +1,3 @@
-# IDE
 .idea/
-*.iml
-# Go
+target/
 bin/
-*.exe
-*.dll
-*.so
-*.dylib
-# Test
-*.test
-*.out
-coverage.out
-# OS
-.DS_Store
-Thumbs.db
-CLAUDE.md