fix(segment): correct behavior condition docs and add CDP API pitfall guidance #110

Summary

Multiple documentation errors and missing guidance in the segment and validate-segment skills cause users to write invalid YAML that passes local validation but fails on tdx sg push.

Problems Found

1. type: Behavior is display-only — API requires type: Value

The skill says type: Behavior but the CDP API only accepts type: Value with source/aggregation/filter. Local tdx validator accepts Behavior (it auto-converts on push), but tdx sg push --dry-run fails with server-side YAML validation error.

Current (wrong):
```yaml

• type: Behavior
  attribute: purchase_event
  source: behavior_purchase_history
  ```

Correct:
```yaml

• type: Value
  attribute: ""
  source: behavior_purchase_history
  aggregation:
  type: Count
  filter:
  type: And
  conditions:
  - type: Column
  column: some_column
  operator: { type: Equal, value: 1 }
  ```

2. Behavior filter requires `type: Column`, not `type: Value`

Skill shows `type: Value` inside filter conditions. API rejects this with `INVALID_RULE_TYPE - expected "Column"`. Must use `type: Column` with `column` field (not `attribute`).

3. Behavior source requires filter (BEHAVIOR_SOURCE_MISSING_FILTER)

Skill shows filter as optional. Without filter, the source is ignored and query runs against master table.

4. Nested condition depth limit undocumented (NESTED_CONDITION_GROUP)

Only 1 level of nesting allowed (And inside Or, or Or inside And). No And inside And-inside-Or.

5. Segment references need internal IDs

`include`/`exclude` segment references require TD-generated internal IDs (from `tdx sg pull`). Manual segment names/slugs don't resolve.

6. `--dry-run` validates all files without path arg

`tdx sg push --dry-run` processes all YAML files. Must specify file path to validate a single file.

Files to Update

• `tdx-skills/segment/SKILL.md`
• `tdx-skills/validate-segment/SKILL.md`