feat(projects): add case-insensitive project lookup by name

[CollinsC1O]

Summary

Closes #518

Adds get_project_by_name(name) for case-insensitive project
lookups, backed by a new ProjectByNormalizedName storage index instead of
a full scan via list_projects.

• storage_keys.rs: new ProjectByNormalizedName(String) key
• utils.rs: Utils::normalize_name — ASCII-lowercases a name (safe since
  names are already restricted to alphanumeric/_/-)
• project_registry.rs: register_project / update_project keep the
  normalized index in sync with the existing name index (set on create,
  remove+set on rename); new get_project_by_name does index lookup →
  get_project(id), mirroring get_project_by_slug
• storage_manager.rs: TTL extension for the new index, wired into
  registration, update, and extend_project_full_ttl
• lib.rs: exposes get_project_by_name as a contract entry point
• tests/name_search.rs: exact match, case-insensitive variants,
  nonexistent name, no cross-project collisions, lookup after rename

Note: the issue described ProjectByNormalizedName as an existing index —
it wasn't; only the exact-match ProjectByName existed. This PR adds the
normalized index and its maintenance code.

Test plan

• cargo test name_search once the branch's pre-existing, unrelated
  build breakage is fixed (see below) — verified manually via temporary
  local stubs that the new code compiles and the logic is correct
• Exercise get_project_by_name on testnet with mixed-case input

Known pre-existing issue (unrelated to this PR)

This branch currently fails to build/test independent of this change:
Utils::validate_project_slug, ContractError::ProjectSlugAlreadyExists,
and events::publish_featured_project_event are referenced but don't
exist anywhere in the codebase, and tests/mod.rs declares
error_handling_tests with no matching file. Flagging for visibility;
happy to fix in a follow-up if desired.