Harden PyramidSort input bounds

[krotname]

Motivation

• The CLI trusted unbounded stdin values which could cause NegativeArraySizeException or OutOfMemoryError when allocating Participant[] or growing token buffers.
• The numeric parser accepted arbitrary non-whitespace bytes and performed unchecked integer arithmetic, allowing malformed or overflowing integers to be interpreted as participant counts.
• The token parser doubled a byte buffer with no cap, allowing a single oversized login token to exhaust heap memory.

Description

• Introduce MAX_PARTICIPANTS and MAX_LOGIN_BYTES constants and enforce them before any large allocation.
• Harden FastIn.nextInt() by rejecting sign-without-digit, non-digit characters, and integer overflow with explicit NumberFormatException.
• Cap token growth in FastIn.next() by throwing an IOException when MAX_LOGIN_BYTES is exceeded.
• Validate the participant count in run() (if (n < 0 || n > MAX_PARTICIPANTS)) before calling new Participant[n].
• Add src/test/java/algorithms/sprint5/PyramidSortTest.java with unit tests for integer overflow, oversized login tokens, negative participant counts before allocation, and existing sort behavior.

Testing

• mvn -q -Dtest=algorithms.sprint5.PyramidSortTest test was run and passed after fixing a test invocation detail.
• mvn -q -DskipTests compile was run and completed successfully.
• mvn -q test (full test suite) was run and completed successfully.

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Codex Task

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/main/java/algorithms/sprint5/PyramidSort.java	50.00%	0 Missing and 1 partial ⚠️

📢 Thoughts on this report? Let us know!

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
83.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

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Закрываю как superseded by #116: изменения перенесены в одну проверенную ветку, все review findings учтены; локальный mvn verify прошёл полностью.