fix: Hourly Rate + Formatting

[DylanDevelops]

This pull request adds support for tracking and reporting hourly rates and estimated earnings for time entries in the time tracking application. It introduces a new hourly_rate field to the database, updates the data model, and enhances the statistics output to include estimated earnings by project and in total. Several user-facing messages and formatting details are also improved.

Hourly Rate and Earnings Tracking

• Added a new hourly_rate column to the time_entries table and updated the TimeEntry model to include an optional HourlyRate field. All database access methods now handle this field, allowing each entry to store an hourly rate if available. [1] [2]
• Modified the entry creation logic in cmd/start.go to load the hourly rate from config (if set) and store it with each new entry.
• Updated all relevant database queries and methods (CreateEntry, GetEntry, GetEntries, GetEntriesByProject, GetEntriesByDateRange, etc.) to read and write the hourly_rate field, and to properly set it on the TimeEntry struct if present. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]

Statistics and Reporting Enhancements

• Enhanced the output of the stats command to display total and per-project estimated earnings when any entries have an hourly rate. This is shown in both period and all-time statistics. [1] [2]
• Improved period naming and formatting for statistics output (e.g., "This Week" instead of "This week").

User Experience and Output Improvements

• Standardized user-facing output messages for config source information and error messages in cmd/start.go. [1] [2]
• Changed time formatting in log output to use zero-padded hours for consistency (e.g., "03:04 PM" instead of "3:04 PM").

Codebase Cleanup

• Removed unused import of the config package from cmd/stats.go.