fix(typedef): fix code examples and cross-doc inconsistencies from second review

- Fix code examples hardcoding little-endian: read_string, write_string,
  read_string_indirect now take endian parameter and use match on Endian.
- Fix TUnion dispatch examples: remove undefined functions (read_u8,
  read_field, read_struct, read_f32_raw), remove Value returns
  (contradicts 'no intermediate Value tree'), add endian-aware
  discriminator reading for Uint8/Uint16/Uint32.
- Fix read_f32 example: inline the endian-aware conversion instead of
  calling undefined read_f32_raw; document it as aligned-mode only.
- Fix architecture README: 16→17 kinds in schema-layer and validation
  descriptions.
- Fix ADR-095: clarify validation operates on Value instances, not raw
  byte buffers directly. Fix 'defense in depth' paragraph.
- Fix ADR-097: add §3a defining TRecord 'values' property shape.
- Fix ADR-098: TTimestamp format ISO 8601→RFC 3339.
- Tighten OQ-071 impacts field: state what IS blocked, not just what
  isn't.

docs/architecture/decisions/097-schema-annotations.md

@@ -129,6 +129,26 @@ reserving worst-case space.
   types: `TypeDef:String`, `TypeDef:Bytes`, `TypeDef:Array`,
   `TypeDef:Record`, `TypeDef:Timestamp`.
 
+### 3a. TRecord value type
+
+`TypeDef:Record` is a string-keyed map. The value type is declared via
+the `"values"` property in the schema:
+
+```json
+{
+  "TypeDef:Record": true,
+  "values": { "TypeDef:Float32": true }
+}
+```
+
+- `"values"` is a schema object declaring the `TypeDef:*` kind of all
+  values in the record. All values share the same type.
+- The binary layout is a count-prefixed sequence of `(key, value)` pairs:
+  `[count: u32][key_len: u32][key_bytes][value_len: u32][value_bytes]...`.
+- The count prefix respects the schema's endianness.
+- In aligned static mode with `maxLength`, the entire record is reserved
+  at `maxLength` bytes (zero-padded).
+
 ### 4. TUnion discriminators
 
 **Two discriminator kinds: byte-offset (protocol dispatch) and