fix: safely encode dynamic URL path segments

[shadrach68]

closes #20

Task Summary

Safely encode dynamic URL path segments before they are interpolated into service endpoint paths.

Background / Context

Service methods were building paths with string interpolation, such as /guilds/${guildId}/roles and /guilds/${guildId}/members/${walletAddress}/roles. If a dynamic value contained reserved URL characters (like /, #, or spaces), the request path could become malformed. This PR ensures all dynamic path values are encoded with encodeURIComponent before being inserted into endpoint paths, while keeping query parameter handling separate and preserving existing input validation.

Changes Made

• Created encodePathSegment helper utility in src/utils/formatting.ts.
• Updated RolesService and GuildsService to safely encode guildId and walletAddress parameters.
• Added test coverage in tests/services.test.ts to assert that reserved characters like / and spaces are accurately encoded (e.g. %2F and %20).

Acceptance Criteria Met

• guildId values used in path segments are URL-encoded
• walletAddress values used in path segments are URL-encoded
• Existing endpoints still produce the same path for simple IDs
• Tests cover at least one ID containing a reserved character such as /, #, or space

Testing Requirements

• pnpm typecheck passes
• pnpm lint passes
• pnpm test:run passes — new behaviour has test coverage
• pnpm build succeeds

Semver Impact

Patch