feat(contract): add get_config getter for operational limits

[dezzy-music]

Description

Introduces a public get_config getter on DepRaderRouter that returns the contract's fixed operational limits (REVIEW_WINDOW_SECS, MAX_BOUNTY_DURATION_SECS, MAX_CLAIMS_PER_BOUNTY, MAX_REF_LEN) as a typed Config struct. This prevents frontends and clients from hardcoding constants and silently diverging upon contract updates.

Closes #173

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Tasks Completed

• Defined Config struct with review_window_secs, max_bounty_duration_secs, max_claims_per_bounty, and max_ref_len.
• Implemented pub fn get_config(_env: Env) -> Config on DepRaderRouter.
• Added unit test test_get_config_matches_constants verifying that get_config strictly matches the contract's defined constants.
• Updated test snapshots (test_get_config_matches_constants.1.json).
• Documented the change in PROGRESS.md.

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Acceptance Criteria

• A test asserts the getter matches the constants: test_get_config_matches_constants
• cargo fmt, cargo clippy -- -D warnings and cargo test --workspace pass
• Contract test snapshots are updated and the wasm build succeeds
• PROGRESS.md entry added, and the PR description includes Closes #173

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Stellar Address (Stellar Wave Program)

GDLCJGQLXZGDAAT5QGRF6FM2MBEER3FPYGCSVPXYL47G2ABIOX2M2S6K