Support stable runtime TA lengths

[luisleo526]

Summary

• allow input/timeframe/math-derived stable TA constructor lengths while keeping series-dependent dynamic lengths rejected
• add dead-function ownership handling for cloned TA/fixnan sites
• support Pine const/simple/series qualifier declarations and generic input() getter inference
• fix top-level fixnan member aliasing with function-owned fixnan state

Verification

• lead: python -m pytest tests/test_codegen_ta_derived_length.py tests/test_compile_smoke.py tests/test_codegen_new.py -> 201 passed
• R7: focused suite 201 passed; compile corpus 254 passed; remaining suite 1154 passed / 1 skipped
• Cluster A rerun: 4/5 prior TA-length blockers now compile/run or no-trade; series-dependent wellmanapex remains rejected by design