Validate sprint8 CLI input (Crib & PackedPrefix)

[krotname]

Motivation

• The Crib and PackedPrefix CLI solvers assumed well-formed, lowercase input and unbounded dictionary sizes, which allowed crafted stdin to trigger uncaught runtime exceptions (e.g. ArrayIndexOutOfBoundsException and NegativeArraySizeException) and crash the process.
• The change prevents availability issues by validating grammar, character ranges, bracket balance, and numeric bounds before using input as array indexes or allocation sizes.

Description

• Added isLowercaseWord checks in Crib.solve to reject any text or dictionary word containing characters outside 'a'..'z', and changed the aggregate dictionary-size accumulator to long with a guard against overflow before allocating the trie.
• Added an early check in Crib.run to reject negative n and return NO instead of allocating arrays with attacker-controlled sizes.
• Added isValidPacked in PackedPrefix to validate encoded-string grammar (lowercase literals, digits followed by '[', bracket balance, no unmatched ], and disallowed characters) and applied it to the first and each subsequent packed string before decoding/comparison.
• Hardened PackedPrefix.run to handle n <= 0 and to stop/return early when invalid packed input is detected, avoiding use of matchingBracket or frame stacks on malformed strings.

Testing

• Ran the full test suite with Maven using mvn test and observed Tests run: 546, Failures: 0, Errors: 0, Skipped: 0 and BUILD SUCCESS.

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[chatgpt-codex-connector]

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[krotname]

Закрываю как superseded by #116: изменения перенесены в одну проверенную ветку, все review findings учтены; локальный mvn verify прошёл полностью.