fix(codegen): context-sensitive cloning so nested stateful helpers don't share TA/var state

[luisleo526]

Problem

A stateful Pine helper reached through multiple distinct call paths shared one TA member (and one var). Two compounding defects:

1. _ta_site_map poisoning (codegen/base.py): function-local TA sites are shared across clones (clones copy node=orig.node). The _u{n} collision-renamed clone sites overwrote the canonical cs0 entry, so the active-remap lookup missed its base name and every clone collapsed onto one member.
2. Broken nested dispatch (codegen/visit_call.py): a nested helper call inside a clone emitted {G}_cs{enclosing_active_cs}, conflating the callee's own textual call sites with the enclosing function's. For leg (reached via f_get×3 / track / wyckoff×2 / getcur×2 / direct = 9 paths) this produced 5 clones all bound to one shared length-30 member; the other 8 correctly-sized ta::Highest/Lowest members were declared but dead.

Fix

Add a context-sensitive (call-path) instance pre-pass _build_func_instances: walk the call graph from each natural clone and, per nested stateful call, compose the enclosing clone's active remap with the callee's per-call-site remap:

composed[m] = R_enclosing.get(R_callee_cs[m], R_callee_cs[m])

When the composition equals the callee's natural cs{j} remap it reuses the existing {G}_cs{j} clone — so output is byte-identical for the common single-caller case. Otherwise it mints a fresh instance bound to the path-specific TA members and fresh var members (so two paths never share scalar state). _instance_dispatch then authoritatively routes each nested call.

Validation

	result
jevondijefferson-big-breakout (leg reached via 9 paths)	0.9% → 36.1% match vs TV (count 143→172, price-exact 94.9% of matched); deterministic ×3
full gate PINEFORGE_ENGINE_INCLUDE=... pytest	1386 passed, 1 skipped, 0 failed (1384 baseline + 2 new tests; 254-strategy corpus compile all green)
87-strategy behavioral sweep	byte-identical transpile on 86/87, only jevondijefferson moved (improved) — zero regressions

New test_nested_helper_multi_path_distinct_ta_members / ..._distinct_var_state have teeth (fail on the unpatched tree: only 2 clones + dead members).

Note: the residual to 36% on jevondijefferson is a window-start warmup transient (path-dependent state needs TV's full pre-range history), not a fill-model or accounting gap — out of scope for this codegen fix.

🤖 Generated with Claude Code