lib: rename stdlib surface to Hare names; add endian/math

Sweeping rename so the lib/ surface mirrors Hare's stdlib spellings.
- ascii: rune-taking predicates; ishex -> isxdigit
- bufio: rinit -> init; take1/takeline -> readbyte/readline
- bytes: indexsub -> index
- encoding/utf8: runelen -> runesz
- errors: eEOF/eShortRead/... -> eof/underread/...
- fmt: errln -> errorln; println/fprintln return i64
- os: readfull/writefull -> readall/writeall; unlink -> remove
- path: isabs -> abs; drop lastindex (now strings.rbyteindex)
- strconv: u64toa/i64toa -> u64tos/i64tos; parse64/parseu64 -> stoi64/stou64
- strings: drop len/isempty; equal -> compare; indexbyte -> byteindex; +rbyteindex
- types: drop numeric helpers (moved to math)
- new lib/endian (htonu16/ntohu16), lib/math (absi32/absi64)
- net: drop htons (use endian.htonu16)

Callers in selfhost/, lib/ww/, cmd/w6c/cgen.c, and test/wcc/700_e2e.c
updated to match.

lib/ww/ast.ww

@@ -256,12 +256,12 @@ fn pr(fd: i32, n: *node, d: i32) void = {
 	if (n.kind == N_INTLIT) {
 		putc1(fd, 32u8);
 		let buf: [32]u8;
-		let m: i32 = strconv.u64toa(buf[0:32], n.uval);
+		let m: i32 = strconv.u64tos(buf[0:32], n.uval);
 		os.write(fd, buf.ptr, m: u64);
 	} else { if (n.kind == N_RUNELIT) {
 		putc1(fd, 32u8);
 		let buf: [32]u8;
-		let m: i32 = strconv.u64toa(buf[0:32], n.uval);
+		let m: i32 = strconv.u64tos(buf[0:32], n.uval);
 		os.write(fd, buf.ptr, m: u64);
 	} else { if (
 		n.kind == N_STRLIT  ||

lib/ww/lex/lex.ww

@@ -230,18 +230,18 @@ fn escape(l: *lex, out: *i32) bool = {
 		let lo: i32 = lget(l);
 		if (hi < 0) { return false; };
 		if (lo < 0) { return false; };
-		if (!ascii.ishex(hi: u8)) {
+		if (!ascii.isxdigit(hi: rune)) {
 			let cp: pos; curpos(l, &cp);
 			errat(l, &cp, "bad \\x escape");
 			return false;
 		};
-		if (!ascii.ishex(lo: u8)) {
+		if (!ascii.isxdigit(lo: rune)) {
 			let cp: pos; curpos(l, &cp);
 			errat(l, &cp, "bad \\x escape");
 			return false;
 		};
-		let h: i32 = ascii.digitval(hi: u8);
-		let lv: i32 = ascii.digitval(lo: u8);
+		let h: i32 = ascii.digitval(hi: rune);
+		let lv: i32 = ascii.digitval(lo: rune);
 		*out = (h << 4) | lv;
 		return true;
 	};
@@ -255,7 +255,7 @@ fn scandecimalrun(l: *lex) void = {
 	for (true) {
 		let c: i32 = lpeek(l, 0u64);
 		if (c < 0) { break; };
-		if (!ascii.isdigit(c: u8)) {
+		if (!ascii.isdigit(c: rune)) {
 			if (c != 95) { break; };
 		};
 		lget(l);
@@ -266,7 +266,7 @@ fn scanhexrun(l: *lex) void = {
 	for (true) {
 		let c: i32 = lpeek(l, 0u64);
 		if (c < 0) { break; };
-		if (!ascii.ishex(c: u8)) {
+		if (!ascii.isxdigit(c: rune)) {
 			if (c != 95) { break; };
 		};
 		lget(l);
@@ -305,7 +305,7 @@ fn scanexp(l: *lex) void = {
 	for (true) {
 		let c: i32 = lpeek(l, 0u64);
 		if (c < 0) { break; };
-		if (!ascii.isdigit(c: u8)) { break; };
+		if (!ascii.isdigit(c: rune)) { break; };
 		lget(l);
 	};
 };
@@ -390,12 +390,12 @@ fn lexnum(l: *lex, start: *pos, out: *tok) void = {
 
 	let pc: i32 = lpeek(l, 0u64);
 	if (pc >= 0) {
-		if (ascii.isidstart(pc: u8)) {
+		if (ascii.isidstart(pc: rune)) {
 			let sb: u64 = l.lpos;
 			for (true) {
 				let cc: i32 = lpeek(l, 0u64);
 				if (cc < 0) { break; };
-				if (!ascii.isidpart(cc: u8)) { break; };
+				if (!ascii.isidpart(cc: rune)) { break; };
 				lget(l);
 			};
 			let sl: u64 = l.lpos - sb;
@@ -439,7 +439,7 @@ fn lexident(l: *lex, start: *pos, out: *tok) void = {
 	for (true) {
 		let c: i32 = lpeek(l, 0u64);
 		if (c < 0) { break; };
-		if (!ascii.isidpart(c: u8)) { break; };
+		if (!ascii.isidpart(c: rune)) { break; };
 		lget(l);
 	};
 	let n: u64 = l.lpos - begin;
@@ -588,8 +588,8 @@ export fn lexnext(l: *lex, out: *tok) void = {
 	let c: i32 = lpeek(l, 0u64);
 
 	if (c >= 0) {
-		if (ascii.isidstart(c: u8)) { lexident(l, &start, out); return; };
-		if (ascii.isdigit(c: u8))   { lexnum(l, &start, out); return; };
+		if (ascii.isidstart(c: rune)) { lexident(l, &start, out); return; };
+		if (ascii.isdigit(c: rune))   { lexnum(l, &start, out); return; };
 	};
 
 	if (c == 34) { lget(l); lexstr(l, &start, out); return; };

lib/ww/lex/tok.ww

@@ -372,10 +372,10 @@ export fn tokprint(fd: i32, t: *tok) void = {
 	};
 	fputcbyte(fd, 58u8);	// ':'
 	let buf: [32]u8;
-	let n: i32 = strconv.i64toa(buf[0:32], t.line: i64);
+	let n: i32 = strconv.i64tos(buf[0:32], t.line: i64);
 	os.write(fd, buf.ptr, n: u64);
 	fputcbyte(fd, 58u8);
-	n = strconv.i64toa(buf[0:32], t.col: i64);
+	n = strconv.i64tos(buf[0:32], t.col: i64);
 	os.write(fd, buf.ptr, n: u64);
 	fputcbyte(fd, 32u8);	// ' '
 	fputsstr(fd, tokname(t.kind));
@@ -391,11 +391,11 @@ export fn tokprint(fd: i32, t: *tok) void = {
 		fputq(fd, ttext.ptr, ttext.len);
 	} else { if (t.kind == TK_INT) {
 		fputcbyte(fd, 32u8);
-		n = strconv.u64toa(buf[0:32], t.uval);
+		n = strconv.u64tos(buf[0:32], t.uval);
 		os.write(fd, buf.ptr, n: u64);
 	} else { if (t.kind == TK_RUNE) {
 		fputcbyte(fd, 32u8);
-		n = strconv.u64toa(buf[0:32], t.uval);
+		n = strconv.u64tos(buf[0:32], t.uval);
 		os.write(fd, buf.ptr, n: u64);
 	};};};};};
 	// TK_FLOAT is intentionally not handled here — %g formatting