When collectConstLocals proves a LOCAL is only ever read, not
written beyond its literal init, every read site gets the literal
substituted inline — which means the init itself has no live
reader. Skip emitting the PushXxx/PopLocalFast pair for those
LOCALs in both top-of-function and mid-body decls.
On a function with `LOCAL nBuf := 100, sTag := "x", bFlag := .T.`,
all three inits drop out (6 VM ops saved in the prologue), while
the still-written `LOCAL nSum := 0` init stays. Harbour compat
56/56, FiveSql2 43/43.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>