Add JSON5 support, --json CLI flag, typed getters, and improve YAML quoting

- Updated JSON resolver to use gjson library for JSON5 support (comments, trailing commas)
- Added --json flag to CLI tool for JSON output format
- Added typed getter methods: GetInt(), GetUint(), GetFloat(), GetBool(), GetBytes()
- GetBytes() supports human-readable formats like "10G", "20KiB" via go-humanize
- Fixed YAML interpolation to always quote output values for safety
- Updated README to clarify YAML-only input and automatic quoting behavior
- Added .gitignore to exclude compiled binary
- Fixed test config files to use unquoted interpolation syntax
- Updated tests to expect quoted interpolation output

test/config.yaml

@@ -6,20 +6,20 @@ server:
   hostname: ${EXEC:hostname}
   
 machine:
-  id: "${FILE:./test/machine-id}"
-  cores: "${EXEC:echo 4}"
+  id: ${FILE:./test/machine-id}
+  cores: ${EXEC:echo 4}
 
 api:
-  endpoint: "${JSON:./test/hosts.json:'.api_endpoints.primary'}"
-  tls_host: "${JSON:./test/hosts.json:'.tls_sni_host[0]'}"
+  endpoint: ${JSON:./test/hosts.json:api_endpoints.primary}
+  tls_host: ${JSON:./test/hosts.json:tls_sni_host.0}
 
 database:
-  host: "${YAML:./test/data.yaml:'.database.host'}"
-  version: "${YAML:./test/data.yaml:'.version'}"
+  host: ${YAML:./test/data.yaml:'.database.host'}
+  version: ${YAML:./test/data.yaml:'.version'}
 
 nested:
-  value: "${ENV:NESTED_${ENV:TEST_ENV_SUFFIX}}"
+  value: ${ENV:NESTED_${ENV:TEST_ENV_SUFFIX}}
 
 env:
   INJECTED_VAR: "injected-value"
-  COMPUTED_VAR: "${EXEC:echo computed}"
+  COMPUTED_VAR: ${EXEC:echo computed}