Add 5000 character hard limit for lyrics field

Suno caps the lyrics window at 5000 characters including all
structure tags and instruction brackets. Added to HARD CONSTRAINTS
so the LLM respects the limit when generating.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## [1.3.2] - 2026-02-24
+
+### Added
+- **Lyrics field 5000 character hard limit** — Added to HARD CONSTRAINTS in knowledge base. The limit includes all structure tags, instruction brackets, and lyrics text (everything in the lyrics window counts toward the cap). Prevents generated lyrics from exceeding Suno's input limit.
+
 ## [1.3.1] - 2026-02-20
 
 ### Fixed

knowledge_base.py

@@ -17,7 +17,7 @@ Tag Weighting: Position 1 = ~50% influence, Position 2 = ~25%, Position 3 = ~12.
 
 Style Prompt: 200-400 chars optimal (sweet spot 250-350). Beyond 400 = dilution and ignored descriptors.
 
-Lyrics Field: Use structure tags on their own lines. Keep section-specific changes, performance cues, and actual lyrics here. BPM can appear in both style prompt AND lyrics (useful for per-section tempo changes like [BPM: 140] before [Chorus]). Key goes in STYLE PROMPT ONLY, do NOT repeat in lyrics.
+Lyrics Field: 5000 character hard limit (including ALL structure tags, instruction brackets, and lyrics text — everything in the lyrics window counts). Use structure tags on their own lines. Keep section-specific changes, performance cues, and actual lyrics here. BPM can appear in both style prompt AND lyrics (useful for per-section tempo changes like [BPM: 140] before [Chorus]). Key goes in STYLE PROMPT ONLY, do NOT repeat in lyrics.
 
 BANNED (Suno ignores these): Frequency specs (40Hz, 2kHz), decibel specs (-6dB, -30dB), time-based specs (6-second decay), DAW terms (sidechain compression, transient shaping), bit depth (12-bit reduction). Mastering LUFS specs (-14 LUFS, -3 dBTP) are low-sensitivity and unreliable — Suno may approximate but cannot guarantee exact values.