Move docs/ package mirror into document-navigator plugin

Relocate the ~6k-file docs tree from the repo root into
plugins/document-navigator/docs/ so the plugin is self-contained and
portable. docs/superpowers/ (specs and plans) stays at the repo root.

Moved via cp+rm rather than git mv because directory rename() fails with
EPERM on this WSL /mnt DrvFs mount; git rename-detection pairs the
identical-content files at commit time.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugins/document-navigator/docs/foundation/flow/streams-metadata/README.md

@@ -0,0 +1,88 @@
+# @suaveplan/streams-metadata - Universal stream transforms that detect MIME type and extract EXIF/IPTC/XMP image metadata via @suaveplan/streams BaseTransform
+
+Universal stream transforms that detect MIME type and extract
+EXIF/IPTC/XMP image metadata from buffered `Uint8Array` payloads. Three
+composable transforms (`MimeTransform`, `ExifTransform`, and the wrapping
+`MetadataTransform`) each extend `BaseTransform` from `@suaveplan/streams`
+and expose a typed event surface through the inherited `on`/`off` API.
+
+<!-- begin:auto-docs -->
+## Documentation tree
+
+- [errors](./src/errors/errors.md) — Stable error registry for the `@suaveplan/streams-metadata` package. Every failure surface produced by `MimeTransform`,…
+  - [errors](./src/errors/errors.md) — Stable error registry for the `@suaveplan/streams-metadata` package. Every failure surface produced by `MimeTransform`,…
+- [events](./src/events/events.md) — Declares the typed `StreamsMetadataEvents` map consumed by every transform in this package. `BaseTransform` fro…
+  - [events](./src/events/events.md) — Declares the typed `StreamsMetadataEvents` map consumed by every transform in this package. `BaseTransform` fro…
+- [exif](./src/exif/exif.md) — `ExifTransform` is a universal stream transform that extracts `ImageMetadata` via `@suaveplan/exif::readMetadata`…
+  - [exif](./src/exif/exif.md) — `ExifTransform` is a universal stream transform that extracts `ImageMetadata` via `@suaveplan/exif::readMetadata`…
+- [metadata](./src/metadata/metadata.md) — `MetadataTransform` is the high-level composing wrapper around `MimeTransform` and `ExifTransform`. A single instance r…
+  - [metadata](./src/metadata/metadata.md) — `MetadataTransform` is the high-level composing wrapper around `MimeTransform` and `ExifTransform`. A single instance r…
+- [mime](./src/mime/mime.md) — `MimeTransform` is a universal stream transform that decides the MIME type of a buffered binary payload and (in `e…
+  - [mime](./src/mime/mime.md) — `MimeTransform` is a universal stream transform that decides the MIME type of a buffered binary payload and (in `e…
+- [payload](./src/types/payload.md) — Public type contract shared by every `@suaveplan/streams-metadata` transform. Callers and library code agree on the sha…
+- [process-options](./src/types/process-options.md) — Defines the `ProcessOptions` shape accepted by every `@suaveplan/streams-metadata` transform's `process(input, options?…
+<!-- end:auto-docs -->
+
+## Install
+
+```bash
+bun add @suaveplan/streams-metadata
+```
+
+## Quick start
+
+```ts
+import { MetadataTransform } from "@suaveplan/streams-metadata";
+
+const transform = new MetadataTransform();
+const result = await transform.process({ bytes: imageBytes, name: "photo.jpg" });
+
+console.log(result.mime?.mimeType); // "image/jpeg"
+console.log(result.exif?.width);    // 1920
+```
+
+## Manual composition
+
+Use `MimeTransform` and `ExifTransform` separately when you need
+fine-grained control over each stage or want to run only one of them:
+
+```ts
+import { ExifTransform, MimeTransform } from "@suaveplan/streams-metadata";
+
+const mime = new MimeTransform();
+const exif = new ExifTransform({ read: { skipXmp: true } });
+
+mime.on("mime:detected", (r) => console.log("MIME:", r.mimeType, "(source:", r.source, ")"));
+exif.on("exif:detected", (m) => console.log("Dimensions:", m.width, "x", m.height));
+
+const afterMime = await mime.process({ bytes: imageBytes, name: "photo.jpg" });
+const afterExif = await exif.process(afterMime);
+```
+
+## Error handling
+
+`MetadataTransform` catches errors from either child transform, emits
+`metadata:error` with the thrown value, and returns the original input
+reference so the pipeline continues. `MimeTransform` never throws for
+unknown bytes — the fallback is `application/octet-stream`. `ExifTransform`
+wraps every reader exception as `ExifFailedError`
+(`STREAMS_METADATA.EXIF_FAILED`) preserving the original `cause`.
+
+## Modules
+
+- [`src/mime/mime.md`](src/mime/mime.md) — MIME detection from magic bytes
+  and file extension.
+- [`src/exif/exif.md`](src/exif/exif.md) — EXIF / IPTC / XMP image metadata
+  extraction via `@suaveplan/exif`.
+- [`src/metadata/metadata.md`](src/metadata/metadata.md) — composing
+  wrapper around both transforms with event forwarding.
+- [`src/events/events.md`](src/events/events.md) — full
+  `StreamsMetadataEvents` reference.
+- [`src/errors/errors.md`](src/errors/errors.md) — `StreamsMetadataError`,
+  factory subclasses, and the `STREAMS_METADATA_CODES` registry.
+- [`src/types/payload.md`](src/types/payload.md) — `MetadataPayload`,
+  `EnrichedPayload`, `MimeDetectionResult`, `MetadataMode`.
+- [`src/types/process-options.md`](src/types/process-options.md) — runtime
+  `ProcessOptions` shape (signal / clock / logger) accepted by every
+  transform.
+