feat(sarvam): expose max_session_duration as TTS constructor parameter

[KeWang0622]

Summary

Closes #5268

The Sarvam TTS plugin's WebSocket connection pool hardcodes max_session_duration to 3600 seconds, making it impossible to control connection reuse without reaching into private attributes (tts._pool._max_session_duration = 0).

This PR exposes max_session_duration as a public constructor parameter on sarvam.TTS:

tts = sarvam.TTS(
    target_language_code="hi-IN",
    model="bulbul:v3",
    speaker="ritu",
    max_session_duration=0,  # fresh connection per request
)

Changes:

• Add max_session_duration field to SarvamTTSOptions dataclass (default: 3600)
• Add max_session_duration parameter to TTS.__init__() with validation (>= 0)
• Pass the value through to utils.ConnectionPool instead of the hardcoded 3600
• Update docstrings for both the dataclass and the constructor

Behavior:

• max_session_duration=3600 (default) — existing behavior, connections reused for up to 1 hour
• max_session_duration=0 — fresh WebSocket per request, no reuse (may improve audio quality as noted in the issue)
• max_session_duration=N — custom reuse window in seconds

No breaking changes — the default matches the previous hardcoded value.

Test plan

• Verify sarvam.TTS(target_language_code="hi-IN", max_session_duration=0) creates a fresh connection per request
• Verify default behavior (no max_session_duration arg) is unchanged
• Verify max_session_duration=-1 raises ValueError
• ruff check and ruff format pass

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

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[KeWang0622]

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