[Feature]: Proposal: Amplify continuous product discovery/validation thinking, planning and execution in Spec Kit

The current Specification-Driven Development (SDD) framework in Spec Kit is highly effective at automating the path from "Intent" to "Delivery". However, it currently lacks a native mechanism to:

1. Distinguish between building for **learning** (uncertainty) vs. building for **delivery** (certainty). For example - for a requirement that [NEEDS CLARIFICATION] the assumption is they are cleared ahead of implementation. How could we allow for a learning plan that gets clarity through the agentic loop? (e.g. through learning stories, spikes, etc. )

2. Encourage closing the feedback loop using real-world **Validation** after an implementation slice is delivered. (it leads to "working tested software" but not necessarily "useful software")

How could we weave into Spec-kit some ideas like:
- Focusing on outcomes/behaviors (who does what by how much) rather than outputs/deliverables?
- risk/uncertainty/clarification taxonomy - e.g. level of uncertainty, type of uncertainty (desirability, viability to run efficiently, feasibility to build, time to build)
- Derisking through discovery when appropriate?
- Maintaing the spec as a living document throughout the discovery/derisking process.

## Value Proposition
- **Reduced Waste**: Prevents over-engineering features with low product conviction.
- **Improved Alignment**: Forces a shared understanding of what we *know* vs. what we are *guessing*.
- **Full Life-cycle SDD**: Moves SDD from a technical execution framework to a product development operating model.

Would love to get feedback on this direction and whether it aligns with the long-term vision of Spec Kit.

PS
some ideas for how to go about doing this below:
### 1. Conviction-Based Specification
Update the `/speckit.specify` command and the `spec-template.md` to:
- Assess and declare a **Conviction Level** (High, Medium, Low).
- Replace generic "Assumptions" with categorized **Leap of Faith Assumptions (LOFAs)** (Value, Usability, Feasibility, Viability).
- Include "Hypotheses to Validate" within User Stories for low/medium conviction features.

### 2. Strategic Planning (Learning vs. Delivery)
Update the `/speckit.plan` command to branch its strategy based on conviction:
- **Low/Medium Conviction** -> A **Learning-Oriented Plan** prioritized for telemetry, scaffolding, and experiment validation.
- **High Conviction** -> A **Delivery-Oriented Plan** prioritized for robustness and scale.

### 3. Closing the Loop: The `/speckit.validate` Command
Add a new command to finalize the "SDD Cycle":
- `/speckit.validate`: Takes real-world signals/telemetry/feedback and compares them against the LOFAs in the spec.
- Outputs a **Validation Report** that recommends a **Pivot**, **Persevere**, or **Kill** decision.

### Proposed Solution

How could we weave into Spec-kit some ideas like:
- Focusing on outcomes/behaviors (who does what by how much) rather than outputs/deliverables?
- risk/uncertainty/clarification taxonomy - e.g. level of uncertainty, type of uncertainty (desirability, viability to run efficiently, feasibility to build, time to build)
- Derisking through discovery when appropriate?
- Maintaing the spec as a living document throughout the discovery/derisking process.

### Alternatives Considered

_No response_

### Component

Spec templates (BDD, Testing Strategy, etc.)

### AI Agent (if applicable)

None

### Use Cases

When working on products/features with medium/high uncertainty, especially related to desirability/value.

### Acceptance Criteria

_No response_

### Additional Context

_No response_