p0-1: kb-parse-types thin parser-intermediate crate

Adds the kb-parse-types crate per design §3.7b. Depends only on kb-core
+ serde/thiserror — never on parser libraries. Defines:

- ParsedBlock + ParsedBlockKind + ParsedPayload (8 variants matching
  Block variants in kb-core).
- Warning + WarningKind for parser diagnostics.
- Forward-declared ParsedImageRegion / ParsedPdfPage / ParsedAudioSegment
  shells for P6/P7/P8.

`cargo tree -p kb-parse-types` shows only kb-core, serde, and thiserror.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/kb-parse-types/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name          = "kb-parse-types"
+version       = { workspace = true }
+edition       = { workspace = true }
+rust-version  = { workspace = true }
+license       = { workspace = true }
+repository    = { workspace = true }
+description   = "Parser intermediate representations (no parser libs allowed)"
+
+[dependencies]
+kb-core    = { path = "../kb-core" }
+serde      = { workspace = true }
+thiserror  = { workspace = true }

crates/kb-parse-types/src/lib.rs

@@ -0,0 +1,98 @@
+//! `kb-parse-types` — parser intermediate representations (§3.7b).
+//!
+//! Depends ONLY on `kb-core`. Must NOT depend on any parser library
+//! (`pulldown-cmark`, `pdf-extract`, `image`, `whisper-rs`, …) and must
+//! NOT depend on any other `kb-*` crate.
+
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct ParsedBlock {
+    pub kind: ParsedBlockKind,
+    pub heading_path: Vec<String>,
+    pub source_span: kb_core::SourceSpan,
+    pub payload: ParsedPayload,
+}
+
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum ParsedBlockKind {
+    Heading,
+    Paragraph,
+    List,
+    Code,
+    Table,
+    Quote,
+    ImageRef,
+    AudioRef,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase", tag = "kind")]
+pub enum ParsedPayload {
+    Heading {
+        level: u8,
+        text: String,
+    },
+    Paragraph {
+        text: String,
+        inlines: Vec<kb_core::Inline>,
+    },
+    List {
+        ordered: bool,
+        items: Vec<Vec<kb_core::Inline>>,
+    },
+    Code {
+        lang: Option<String>,
+        code: String,
+    },
+    Table {
+        headers: Vec<String>,
+        rows: Vec<Vec<String>>,
+    },
+    Quote {
+        text: String,
+        inlines: Vec<kb_core::Inline>,
+    },
+    ImageRef {
+        src: String,
+        alt: String,
+    },
+    /// `duration_ms` is filled in by the extractor before chunking — see
+    /// design §3.7b.
+    AudioRef {
+        src: String,
+    },
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct Warning {
+    pub kind: WarningKind,
+    pub note: String,
+}
+
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum WarningKind {
+    MalformedFrontmatter,
+    MalformedTable,
+    EncodingFallback,
+    ExtractFailed,
+}
+
+// Forward-declared (P6/P7/P8). Bodies stay minimal for now.
+#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
+pub struct ParsedImageRegion;
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct ParsedPdfPage {
+    pub page: u32,
+    pub text: String,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct ParsedAudioSegment {
+    pub start_ms: u64,
+    pub end_ms: u64,
+    pub text: String,
+}