[WOOMOB-3739] Add the Product Detail Compose screen (2/3)

[hichamboushaba]

Description

Stacked on #16393 — review after it. Part 2 of 3; followed by #16395.

Part of WOOMOB-3739 — does not close the ticket.

This is part 2 of 3 in the Product Detail Compose migration stack. It adds the complete mode-agnostic Product Detail Compose renderer without routing production traffic to it yet.

Add and Edit share immutable row models, image/header states, title editing and restoration, accessibility semantics, previews, and a lazy scrolling body. Navigation, analytics, toolbar/menu, gallery ownership, and Fragment orchestration remain outside the renderer.

The final PR performs the runtime cutover and legacy cleanup.

Test Steps

1. Inspect the Existing Product and Add Product Compose previews in light and dark themes.
2. Inspect loading, empty, error, image, long-content, large-font, RTL, and landscape variants.
3. Run ./gradlew :WooCommerce:assembleWasabiDebug.
4. Run the AI attribution unit test and ./gradlew :WooCommerce:compileWasabiDebugAndroidTestKotlin.
5. Run ./gradlew detektAll.

Images/gif

Theme	Existing product	Add product
Light
Dark

• I have considered if this change warrants release notes and have added them to RELEASE-NOTES.txt if necessary. Use the "[Internal]" label for non-user-facing changes.

[dangermattic]

	1 Error
🚫	This PR is tagged with status: do not merge label(s).

	1 Warning
⚠️	This PR is larger than 300 lines of changes. Please consider splitting it into smaller PRs for easier and faster reviews.

Generated by 🚫 Danger

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce Android by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce Android
	Platform	📱 Mobile
	Flavor	Jalapeno
	Build Type	Debug
	Build Number	778
	Version	25.4-rc-1
	Application ID	com.woocommerce.android.prealpha
	Commit	5f6d215
	Installation URL	4mc6q2eg2sg8g

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.

[claude]

AI Code Review - Found 2 potential issues

Overall this is a clean, well-structured set of Compose primitives for the shared Product Detail screen. State handling in ProductDetailEditableField, the AI-attribution styling, and the divider/indent logic all read well, and the extracted pure helpers plus previews are a nice touch. Two points below; only the first is a possible behaviour bug.

PR housekeeping

• Applied repo AGENTS.md/CLAUDE.md guidance (Store Management Compose patterns: WooTheme, StateFlow-driven stateless composables, no Android framework leakage).
• product_rating_content_description hardcodes "out of 5" while RATING_STAR_COUNT is a constant; harmless today, just note the two must stay in sync.

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