[security][H7] Migrate off abandoned imgaug to albumentations

[eprifti]

Split out from #10 which covered H2-H6 dep bumps.

Problem: `imgaug==0.4.0` is unmaintained (last release 2020) and pulls vulnerable transitive dependencies (old Shapely, imageio, etc.). It is imported in three files:

• `Create_database/ecg_image_generator/helper_functions.py`
• `Create_database/ecg_image_generator/ImageAugmentation/augment.py`
• `Create_database/ecg_image_generator/CreasesWrinkles/creases.py`

Recommended target: `albumentations>=1.4.0` — actively maintained, similar API surface.

Scope:

1. Map each imgaug transform used to its albumentations equivalent
2. Replace imports and usage in the three files
3. Remove `imgaug==0.4.0` from `requirements.txt`
4. Regenerate or verify dataset output matches (at least qualitatively)

Non-trivial — kept as its own tracking issue rather than bundled.

[eprifti]

@twesemey Thank you — excellent point. You're right that Create_database/ecg_image_generator/ is a vendored copy of alphanumericslab/ecg-image-kit's ecg-image-gen, and security fixes here benefit everyone if pushed upstream.

Planned upstream contributions:

1. Issue at alphanumericslab/ecg-image-kit: describe the accumulated CVEs in the pinned dependencies (requests 2.21.0, tensorflow/keras 2.14.0, opencv-python 4.6, scikit-learn 1.4.2, validators 0.18.2, spacy 3.2.6) and propose the version bumps we adopted here. Also raise the imgaug maintenance concern (this issue).
2. PR at alphanumericslab/ecg-image-kit: port the SSRF fix from HandwrittenText/generate.py (scheme allowlist, timeout, no redirects, raise_for_status) — small and self-contained.

Will update this issue with links once filed.

[eprifti]

Upstream actions filed:

• Security umbrella issue: Security: pinned dependencies in ecg-image-generator have known CVEs; SSRF in HandwrittenText alphanumericslab/ecg-image-kit#22 (CVE list + SSRF context)
• SSRF fix PR: Harden SSRF in HandwrittenText/generate.py alphanumericslab/ecg-image-kit#23