fix: reject duplicate-name uploads and rebuild fresh Files per send

cache() silently lost a FileRef when a list input had two sources
resolving to the same name (two paths with the same basename, or two
discord.File objects with the same .filename): both files were
uploaded (real cost) but the merge step kept only the last, orphaning
the first. _normalize now rejects a duplicate name with DPYCacheError
before any upload happens.

_to_file returned the same discord.File object for a discord.File
source, only mutating .filename. Reusing one File under two keys
swapped filename/URL between refs; reusing a BytesIO-backed File
re-sent 0 bytes; reusing a path-backed File after discord.py's own
close() raised ValueError. _to_file now builds a genuinely distinct
discord.File per send, re-opening a path-backed source or seeking and
copying a caller-supplied stream; an unrebuildable opaque stream now
raises DPYCacheError instead of corrupting or crashing a later send.

Also: lookup() accepts a digit-only message-id string (previously only
bare int fetched directly, a numeric string routed into the jump-url
parser and raised); dropped a redundant discord.Forbidden member from
an except tuple (Forbidden already subclasses HTTPException); tightened
_parse_jump_url's return type off a dead Optional and added `from err`
to its raise.

Signed-off-by: disqualifier <dev@disqualifier.me>

README.md

@@ -9,7 +9,7 @@ bites you.
 ## Install
 
 ```
-dpy_cache @ git+ssh://git@git.rethinkstudios.io/rethink-public/dpy_cache.git@v0.1.0
+dpy_cache @ git+ssh://git@git.rethinkstudios.io/rethink-public/dpy_cache.git@v0.1.1
 ```
 
 ## Usage
@@ -46,6 +46,9 @@ refs = await cache.lookup(result.message_url)   # jump url, message id, or disco
 refs["avatar.png"].url
 ```
 
+`lookup()` accepts a message id as an `int` or as a digit-only `str` (the snowflake shape
+JSON/DBs store), e.g. `cache.lookup("123456789012345678")`.
+
 ## What you inject
 
 A resolved Discord channel object (`discord.abc.Messageable` that supports `.send` and
@@ -58,7 +61,16 @@ first use.
 
 `cache_one` / `cache` accept, per file: `bytes`, a filesystem path (`str` or
 `os.PathLike`), or a `discord.File`. In a **list** input, raw `bytes` have no filename and
-raise `ValueError` — pass a dict `{name: bytes}` or a `discord.File` to name bytes.
+raise `ValueError` — pass a dict `{name: bytes}` or a `discord.File` to name bytes. A
+**list** input whose sources resolve to the same name (two paths with the same basename,
+two `discord.File`s with the same `.filename`, ...) raises `DPYCacheError` before any
+upload — a dict input can't collide since dict keys are already unique.
+
+A `discord.File` source is safe to reuse across multiple names/batches: `cache()` always
+builds a genuinely fresh `discord.File` per send (re-opening a path-backed source, or
+seeking + copying a caller-supplied stream) rather than reusing the object you passed in.
+An opaque stream that can't be safely re-read (already closed, not seekable) raises
+`DPYCacheError` instead of silently sending stale or empty data.
 
 ## Why `resolve()` exists
 
@@ -80,12 +92,26 @@ API. In short:
 - `lookup(message) -> dict[str, FileRef]`
 
 **Fail-loud.** Nothing is swallowed. Lib-specific invariants raise `DPYCacheError`
-(attachment-count mismatch after a send, `cache_url` non-200, a `lookup` jump-URL pointing
-at a different channel than the injected one). Unnamed `bytes` in a list raise `ValueError`.
-Raw Discord errors (`Forbidden` / `HTTPException` / `NotFound`) propagate **unwrapped** so
-you can still branch on Discord's own types.
+(attachment-count mismatch after a send, a duplicate filename in a list input to `cache()`,
+`cache_url` non-200, a `lookup` jump-URL pointing at a different channel than the injected
+one, a `discord.File` source that can't be safely rebuilt for a repeat send). Unnamed
+`bytes` in a list raise `ValueError`. Raw Discord errors (`Forbidden` / `HTTPException` /
+`NotFound`) propagate **unwrapped** so you can still branch on Discord's own types.
 
 ## Versioning
 
 Tagged `vX.Y.Z`; pin a tag in your install line. Targets `discord.py>=2.0` (not
 `discord.py-self`).
+
+### v0.1.1
+
+- `cache()` now rejects a duplicate filename in a **list** input with `DPYCacheError`
+  before any upload, instead of silently uploading both files and losing the first
+  `FileRef` at merge time.
+- `_to_file` now builds a genuinely fresh `discord.File` per send for `discord.File`
+  sources (previously returned the same object, which could swap filename/URL when one
+  `File` was reused under two names, or re-send 0 bytes / raise `ValueError` on a spent
+  stream).
+- `lookup()` now accepts a digit-only message-id string in addition to `int`.
+- Dropped the redundant `discord.Forbidden` member from an `except` tuple (it already
+  subclasses `discord.HTTPException`); no behavior change.