refactor(deps): rename ragflow_deps directory to deps (#21345)

## Summary

Rename the repository dependency-resource directory `ragflow_deps/` to
`deps/`, and update every hardcoded reference to that directory name so
the rename does not break resource loading at build/runtime.

This is not a purely cosmetic rename: the Go runtime hardcodes the
directory name as a resource search path (e.g.
`internal/common/model_assets.go` trimming the `deps/` prefix, and the
tokenizers joining `deps/` into candidate paths), and the Dockerfiles
copy assets into `/ragflow/deps`. Those literals must move together with
the directory, otherwise assets fail to resolve.

## Two intentional exceptions (kept unchanged)

The rename deliberately keeps two names that only *coincidentally*
contained the old string:

- The published image tag `infiniflow/ragflow_deps:latest` (used by
`Dockerfile`, `Dockerfile_base`, docs, and CI `image inspect` checks).
- The CI install path `/opt/ragflow_deps` inside the CI runner image
(`build.sh` `SYSTEM_DEPS_TOKENIZER`).

## Changes

- `git mv ragflow_deps deps`.
- `build.sh`: `CL100K_TABLE_RELPATH`, native asset zip path, and related
references updated to `deps/`.
- `tools/scripts/download_dev_deps.py`: `RAGFLOW_DEPS_DIR` points at
`deps/`.
- Go runtime resource search paths (`internal/common`,
`internal/tokenizer`) updated to the `deps/` layout.
- `Dockerfile` / `Dockerfile_base`: container asset path changed to
`/ragflow/deps`; kept tag `infiniflow/ragflow_deps:latest` unchanged.
- Docs / `AGENTS.md` / CI workflow paths updated to the new directory
name.

## Test plan

- Go unit tests in `internal/common` and `internal/tokenizer` updated to
the new `deps/` layout and pass via `bash build.sh --test`.
- Python download scripts import and build URLs correctly (`py_compile`
clean).
- Added `tools/scripts/test_dep_rename_invariants.py` as a regression
guard asserting the two intentional exceptions (`/opt/ragflow_deps` and
`infiniflow/ragflow_deps`) stay intact, so a future blanket rename
cannot silently regress them.

---

## Follow-up fix (commit 2f6857095d)

The original rename used a blanket `sed s/ragflow_deps/deps/g` and only
selectively reverted `build.sh`. That left two intentionally-kept names
rewritten, which this follow-up restores:

- CI install path `/opt/ragflow_deps` — `sep-tests.yml` had been changed
to read `/opt/deps`, breaking the offline cl100k table fallback (the
cached-image path pointed at a directory that never receives the file).
Restored to `/opt/ragflow_deps`.
- Published image tag `infiniflow/ragflow_deps` — left as bare
`infiniflow/deps` in `sep-tests.yml` comments/echo, `.dockerignore`, and
`Dockerfile` / `Dockerfile_base` error messages. Restored to
`infiniflow/ragflow_deps`.

The regression guard `tools/scripts/test_dep_rename_invariants.py` was
added to prevent recurrence.

README_tr.md

@@ -223,10 +223,10 @@ Ayrıntılar için [hızlı başlangıç kılavuzuna](./docs/quickstart.mdx) bak
 
    ```bash
    uv run tools/scripts/download_dev_deps.py
-   uv run ragflow_deps/download_deps.py
+   uv run deps/download_deps.py
    ```
 
-   `download_dev_deps.py`, pdfium, pdf_oxide, office_oxide ve onnxruntime'ı `~/ragflow-native-libs` altına indirir ve açar; `download_deps.py`, cl100k sözlüğünü, DeepDoc modellerini ve gömme tokenizer varlıklarını `ragflow_deps/` altına indirir. İkisi de Python betiğidir; `uv run`, bildirilen bağımlılıkları (`requests` ve model ile tokenizer indirmeleri için `huggingface-hub`) otomatik olarak kurar. Aynı kaynakları başka şekilde hazırladıysanız bu adımı atlayın. Depo kökünden başlatıldığında Go hizmetleri `internal/rag/res/deepdoc` dizinini otomatik bulur; başka bir dizinden başlatmak için `DEEPDOC_MODEL_DIR` değişkenini o dizinin mutlak yoluna ayarlayın.
+   `download_dev_deps.py`, pdfium, pdf_oxide, office_oxide ve onnxruntime'ı `~/ragflow-native-libs` altına indirir ve açar; `download_deps.py`, cl100k sözlüğünü, DeepDoc modellerini ve gömme tokenizer varlıklarını `deps/` altına indirir. İkisi de Python betiğidir; `uv run`, bildirilen bağımlılıkları (`requests` ve model ile tokenizer indirmeleri için `huggingface-hub`) otomatik olarak kurar. Aynı kaynakları başka şekilde hazırladıysanız bu adımı atlayın. Depo kökünden başlatıldığında Go hizmetleri `internal/rag/res/deepdoc` dizinini otomatik bulur; başka bir dizinden başlatmak için `DEEPDOC_MODEL_DIR` değişkenini o dizinin mutlak yoluna ayarlayın.
 
 3. Hizmetleri derleyin: