…or (#8790)

From #8783 to trigger preview

When source files contain multi-byte UTF-8 characters (e.g. Chinese filenames in SVG imports), the hash placeholder iterator could panic because the computed `search_end` byte offset landed in the middle of a multi-byte character, making `&str[left_pos..search_end]` an invalid slice.

## Changes

- **`crates/rolldown_utils/src/hash_placeholder.rs`** — Replace `str::find` over `self.s[left_pos..search_end]` with `memchr::memmem::find` over `self.s.as_bytes()[left_pos..search_end]`. Since all placeholder delimiters (`!~{`, `}~`) are ASCII, byte-level search is correct and the resulting `right_pos` is always a valid char boundary.
- Add regression tests covering placeholders adjacent to Chinese characters and cases where the 3-byte boundary of a CJK character straddles `search_end`.

```
thread panicked at crates/rolldown_utils/src/hash_placeholder.rs:56:38:
byte index 1045 is not a char boundary; it is inside '级' (bytes 1044..1047) of `...vue.runtime.esm-bundler-!~{001}~.js`...
```

<!-- START COPILOT ORIGINAL PROMPT -->

<details>

<summary>Original prompt</summary>

>
> ----
>
> *This section details on the original issue you should resolve*
>
> <issue_title>[Panic]: A panic occurred during the build process</issue_title>
> <issue_description>### Panic message
>
> ```Shell
> rendering chunks (411)...Rolldown panicked. This is a bug in Rolldown, not your code.
>
> thread '<unnamed>' (39028) panicked at crates\rolldown_utils\src\hash_placeholder.rs:56:38:
> byte index 1045 is not a char boundary; it is inside '级' (bytes 1044..1047) of `import{C as e,D as t,Dt as n,E as r,J as i,K as a,O as o,S as s,Ut as ee,X as c,Z as l,b as u,ct as d,m as f,st as p,vt as m,x as h}from"./vue.runtime.esm-bundler-!~{001}~.js";import{t as g}from"./objectSpread2-!~{003}~.js";import{s as _}from"./router-!~{0`[...]
> Rolldown panicked. This is a bug in Rolldown, not your code.
> Rolldown panicked. This is a bug in Rolldown, not your code.
> note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
> Rolldown panicked. This is a bug in Rolldown, not your code.
> Rolldown panicked. This is a bug in Rolldown, not your code.
>
> thread '<unnamed>' (45852) panicked at crates\rolldown_utils\src\hash_placeholder.rs:56:38:
> byte index 582 is not a char boundary; it is inside '级' (bytes 581..584) of `import{C as e,D as t,Dt as n,J as r,K as i,O as a,Q as o,S as s,T as c,U as l,Ut as u,W as d,b as f,ct as p,m,n as h,st as g,u as _,vt as v,x as y}from"./vue.runtime.esm-bundler-!~{001}~.js";import{a as b}from"./dist-!~{005}~.js";import"./router-!~{00d}~.j`[...]
> Rolldown panicked. This is a bug in Rolldown, not your code.
> ```
>
> ### Reproduction
>
> It seems the issue was related to Chinese characters in my SVG file name. After I renamed the Chinese names  to English, the problem was fixed.
>
> ### System Info
>
> ```Shell
> System:
>     OS: Windows 11 10.0.26200
>     CPU: (22) x64 Intel(R) Core(TM) Ultra 9 185H
>     Memory: 6.36 GB / 31.43 GB
>   Binaries:
>     Node: 22.14.0 - C:\Program Files\nodejs\node.EXE
>     Yarn: 1.22.22 - C:\Users\jay\AppData\Roaming\npm\yarn.CMD
>     npm: 10.9.2 - C:\Program Files\nodejs\npm.CMD
>     pnpm: 10.30.2 - C:\Users\jay\AppData\Roaming\npm\pnpm.CMD
>   Browsers:
>     Chrome: 146.0.7680.154
>     Edge: Chromium (140.0.3485.54)
>     Firefox: 141.0.3 - C:\Program Files\Mozilla Firefox\firefox.exe
>     Internet Explorer: 11.0.26100.7309
> ```
>
> ### Additional context
>
> _No response_</issue_description>
>
> ## Comments on the Issue (you are @copilot in this section)
>
> <comments>
> </comments>
>

</details>

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- Fixes #8782
- Fixes #8795
- Fixes #8806
- Fixes #8808

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