chore: import upstream snapshot with attribution

docs/articles/modules/log.md

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+## When To Use std.log
+
+In Zerolang, use `std.log` for explicit-buffer structured log record formatting.
+
+Runnable today:
+
+| API | Return | Notes |
+| --- | --- | --- |
+| `std.log.levelDebug()` | `String` | Static `debug` level text. |
+| `std.log.levelInfo()` | `String` | Static `info` level text. |
+| `std.log.levelWarn()` | `String` | Static `warn` level text. |
+| `std.log.levelError()` | `String` | Static `error` level text. |
+| `std.log.message(buffer, level, message)` | `Maybe<Span<u8>>` | Writes one newline-terminated JSON Lines record with `level` and `message`. |
+| `std.log.keyValue(buffer, level, key, value)` | `Maybe<Span<u8>>` | Writes one newline-terminated JSON Lines record with `level`, `key`, and `value`. |
+| `std.log.stringField(buffer, key, value)` | `Maybe<Span<u8>>` | Writes one JSON string field fragment. |
+| `std.log.messageField(buffer, level, message, field)` | `Maybe<Span<u8>>` | Writes one JSON Lines message record with one field fragment. |
+| `std.log.redacted(buffer, level, key)` | `Maybe<Span<u8>>` | Writes one JSON Lines record marking a field name as redacted. |
+
+Metadata labels:
+
+- effects: memory; `messageField` also validates JSON field fragments
+- allocation behavior: writes caller buffer; no hidden heap
+- target support: target-neutral
+- error behavior: returns `null` when the buffer is too small or a value cannot be JSON-escaped
+- ownership notes: borrows returned bytes from caller-owned storage
+- example: `examples/std-testing-log.graph`
+
+## Example
+
+```zero
+pub fn main(world: World) -> Void raises {
+    var storage: [128]u8 = [0_u8; 128]
+    var field_storage: [64]u8 = [0_u8; 64]
+    let field: Maybe<Span<u8>> = std.log.stringField(field_storage, "event", "startup")
+    if field.has {
+        let entry: Maybe<Span<u8>> = std.log.messageField(storage, std.log.levelInfo(), "started", field.value)
+        if entry.has {
+            check world.out.write(entry.value)
+        }
+    }
+}
+```
+
+Expected output:
+
+```json
+{"level":"info","message":"started","event":"startup"}
+```
+
+## Design Notes
+
+`std.log` is a formatting surface, not a global logger. The caller owns the
+storage and chooses where to write the resulting span, such as `World.out`, a
+file handle, or a test assertion.
+
+Records use JSON Lines so downstream tools can parse them without guessing at
+ad hoc separators. The helpers write exactly one record and include a trailing
+newline.
+
+`messageField` validates the final JSON object before returning it. Build field
+fragments with `stringField` unless the field fragment is already known to be
+valid JSON.
+
+Use `redacted` for logs that need to state which field was intentionally
+withheld without writing the sensitive value.