Improve analysis UX: algorithm explanations, skeleton loading, auto-expand achieved specs

- Replace terse one-line optimization mode descriptions with clearer multi-sentence
  explanations of how Maximize Count and Priority Order algorithms behave
- Add skeleton loading placeholders on course buttons while analysis is pending
- Auto-expand achieved specializations to show credit breakdown by default
- Add instructional subtitles to Course Selection and Specializations sections
- Make Clear and Clear All buttons more prominent with visible backgrounds

openspec/changes/analysis-ux-improvements/specs/algorithm-explanations/spec.md

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+## ADDED Requirements
+
+### Requirement: Mode description explains practical behavior
+The ModeToggle component SHALL display a multi-sentence description for each optimization mode that explains the algorithm's practical behavior and when a user would choose it.
+
+For "Maximize Count", the description SHALL convey that:
+- The algorithm finds the combination of specializations that achieves the highest count (up to 3).
+- The user's ranking is used only to break ties when multiple combinations achieve the same count.
+
+For "Priority Order", the description SHALL convey that:
+- The algorithm processes specializations in the user's ranked order, top to bottom.
+- It locks in the highest-ranked achievable specialization first, then adds more if feasible.
+- The user's ranking directly controls which specializations are prioritized.
+
+#### Scenario: User selects Maximize Count mode
+- **WHEN** the optimization mode is set to "maximize-count"
+- **THEN** a description is displayed that explains the algorithm finds the largest possible set of specializations and uses ranking only as a tiebreaker
+
+#### Scenario: User selects Priority Order mode
+- **WHEN** the optimization mode is set to "priority-order"
+- **THEN** a description is displayed that explains the algorithm guarantees the top-ranked specialization first and greedily adds more in rank order
+
+#### Scenario: Description updates on mode switch
+- **WHEN** the user switches from one mode to the other
+- **THEN** the description text SHALL update immediately to reflect the newly selected mode

openspec/changes/analysis-ux-improvements/specs/analysis-skeleton-loading/spec.md

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+## ADDED Requirements
+
+### Requirement: Skeleton placeholder during analysis
+When an elective set is not pinned and analysis is pending, the CourseSelection component SHALL display skeleton placeholder elements in place of the course choice buttons.
+
+The skeleton placeholders SHALL:
+- Visually approximate the size and layout of the course choice buttons they replace.
+- Display a pulsing/animated background to indicate loading.
+- Replace the current "analyzing..." text label.
+
+#### Scenario: Analysis pending for an unpinned set
+- **WHEN** an elective set is not pinned AND `loading` is true AND no analysis result exists for that set
+- **THEN** skeleton placeholder rectangles SHALL be displayed instead of course choice buttons
+
+#### Scenario: Analysis completes for a set
+- **WHEN** an analysis result arrives for a previously loading set
+- **THEN** the skeleton placeholders SHALL be replaced with the actual course choice buttons showing analysis data
+
+#### Scenario: Set is already pinned
+- **WHEN** an elective set has a pinned course
+- **THEN** no skeleton placeholders SHALL be shown regardless of loading state

openspec/changes/analysis-ux-improvements/specs/expanded-achieved-specializations/spec.md

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+## ADDED Requirements
+
+### Requirement: Achieved specializations default to expanded
+The SpecializationRanking component SHALL initialize with all achieved specializations in the expanded state, showing their AllocationBreakdown credit list by default.
+
+#### Scenario: Initial render with achieved specializations
+- **WHEN** the SpecializationRanking component renders with one or more achieved specializations
+- **THEN** the AllocationBreakdown (per-course credit list) SHALL be visible for each achieved specialization without user interaction
+
+#### Scenario: Achieved set changes after course selection
+- **WHEN** the set of achieved specializations changes due to a course pin/unpin or ranking reorder
+- **THEN** all newly achieved specializations SHALL be expanded by default
+
+#### Scenario: User manually collapses an achieved specialization
+- **WHEN** the user clicks on an achieved specialization that is currently expanded
+- **THEN** the AllocationBreakdown for that specialization SHALL collapse
+
+#### Scenario: Non-achieved specializations remain non-expandable
+- **WHEN** a specialization has a status other than "achieved"
+- **THEN** it SHALL NOT display an AllocationBreakdown and SHALL NOT be expandable